Commercial Systems

1. http://www.peterdoyleconsultancy.com.au/crops.html#tomatos
Peter Doyle
Peter Doyle, is one of Australia's foremost hydroponics systems consultants and a
passionate advocate for the merits of hydroponics. To Peter, hydroponics offers all the
dynamics of certified organic produce grown in soil; and then some. Hydroponics uses
exactly the same trace elements found in soil but without the soil; it is intensive farming, that
is fungicide and pesticide free and it is grown without synthetic fertilisers. Additionally it is
climate, weather & terrain independent and the methodology that Peter advocates recycles
the nutrient solution and uses less water than alternative methods.
When Peter began commercially growing herbs and vegetables in the early nineties, he set
about researching and developing techniques, methods and materials that inevitably found
their way into the industry through the osmotic relationships he maintains with many leading
suppliers. In 2002, and in answer to the needs of drought stricken Australian farmers, Peter
developed a new hydroponic fodder growing system using a combination of expertise,
experience, knowledge and a unique hydroponic feeding method. Designed to consistently
produce high protein green feed in adverse conditions, the Commercial Hydroponic Fodder
System (CHFS) utilizes environmentally sound WaterWise methods, and as such requires
much less water than field grown crops. The design was granted a patent in 2003.
Now that hydroponically grown fodder is proven for commercial purposes the hydroponic
systems Peter designs for plant cultivation are to be found spread across different parts of
the globe from Morocco to the USA. Consequently many consider him as a leading figure in
the industry worldwide and an Authority on hydroponic system design. More info is available
on the ´Fodder´ link above.
The Consultancy
Aside from operating a commercially successful hydroponic herb growing business Peter
advises government authorities and educational institutions; and designs customised
Hydroponic System solutions and Livestock Fodder Systems for commercial enterprises,
farmers, livestock & agricultural organisations.
Through his consultancy Peter and his team provide customers with either practical,
straightforward information or they design and advise how to set up and run commercial
hydroponic systems.
The response from PDC's clients indicates that what we do is meeting customers'
expectations with consistent results being achieved in all areas of our market. We welcome
and encourage customer communication about new ideas and improvements they have
developed as these can only assist our Company and the industry to move forward in the
direction it must surely go.
On this page you can find a brief overview of the most common crops grown in commercial
hydroponic systems throughout Australia. It is by no means an exhaustive list of these crops,
and we have included it only to serve as a reference point for prospective growers. If the crop
you are thinking about growing is not listed, then please contact us, and we will try to fill in
the gaps for you.
Tomatoes

2. One of the most popular crops grown in hydroponics
today, tomatoes are a good option for hydroponic
growers due to the demand for the fruit throughout
Australia (and the world!). It must be noted however,
that growing tomatoes is not for everyone due the
relatively high labour input required between crops,
and the need to pick quite large numbers on a regular
basis. Care should therefore be taken before
establishing a growing system based around this crop,
and we would always recommend spending some
time on an existing farm to get a feel for the amount of
input required before committing to a commercial
hydroponic tomato system.
There are currently a variety of different methods being used in the hydroponic production of
tomatoes of which the most common are NFT and Drip Irrigation. NFT will provide the
greatest yield at the least cost, but this has not been taken on by all growers yet for variety of
different reasons (mostly related to the saying “If it’s not broke, don’t fix it”). But this is
starting to change, and more and more growers are changing over to NFT.
A major consideration when thinking about setting up a hydroponic tomato farm is the initial
cost involved. Because tomatoes are a vine crop and require support from above, you will
need a hothouse that can support their weight. There are of course plenty of companies out
there that can sell you one of these structures, but it is a major expense, and may place a
strain on your budget. However, if you have a good market for tomatoes, this initial cost can
be quickly recovered.
Tomatoes also require pollination to set their fruit, as well as a environmental management
system to keep require as the plants like them for optimum growth. So be prepared for quite
a sharp initial learning curve if you make the final decision to move into this field of
commercial hydroponic farming, and always remember, you get out what you put in.
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Capsicum
Although capsicum and tomatoes are similar in their method of production, there are some
significant differences. For a start, nearly all capsicum are currently grown in medium based
systems as opposed to NFT. This system utilizes the “batch feeding” technique, which allows
for climatic conditions to dictate the feeding frequency and volume, i.e when it is hot, you
feed more at more regular intervals than when it is cold, to allow for increased uptake by the
plants. It is by all accounts a tried and tested method of growing capsicum with many years
of proven results, and should be carefully considered by all growers looking at starting a
capsicum farm.
However, we are in some ways a “pro NFT”
hydroponic consultancy, and would recommend that
all new growers also have a good look at the nutrient
film technique method before committing to any
commercial growing system. We know that in a well
designed NFT channel, results equal to drip feeding
media based systems are easily obtainable, with a
marked decrease in labor costs. Setup costs are much
the same, with the only difference being how long the
plant is left on the system. In a media based system
plants will tend be grown as perennials and will
produce many sets of fruits throughout the year, but

3. will require a fair amount of attention to ward of pests and long term nutrient imbalances. In
NFT plants tend to be grown as annuals, and therefore only produce fruit for a limited period
of time, but do not tend to suffer from many of the problems associated with the perennials
due to the ability to remove any under productive or diseased plants after a much shorter
period of time. With this type of crop, if the worst happens it is only a minor setback, and can
usually be incorporated into a slightly revised planting schedule.
A couple of other points to note with capsicum are that as with other vine crops, capsicum
require a hothouse or structure that can support the weight of the plant from above, and that
you must always have a very good look at the local market to determine whether or not your
business has the potential to be a success in its early stages before going ahead with your
venture. With capsicum, you are very dependent on your market to make your business
successful, with a relatively small margin for error
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Cucumbers
Cucumbers are in many respects similar to tomatoes
and capsicum in their method of production, with the
most notable difference being their vulnerability to cold
temperatures. The air temperature in the hothouse
cannot be allowed to dip below 70 deg F without
stress occurring to the plant, and the nutrient solution
will normally have to heated as well. This may
increase energy costs significantly in colder regions,
but could also be an advantage to prospective
growers in hotter climates.
Again, as with tomatoes and capsicum, cucumbers
can be grown as either a short term crop, or as a long term crop. Short term NFT crops offer
a considerable saving on labour costs, and as such are being used more and more as the
production method of choice for cucumbers. Other methods of cucumber include drip
irrigation culture into mediums such as perlite and rockwool, and the Deep Flow Technique.
Hothouse structures must be capable of supporting vine crops weight, which coupled with
the need to keep cucumbers over a certain temperature and the potential energy costs
associated with this, mean that careful investigation of your market is essential before
embarking on a cucumber growing venture.
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Herbs
The markets in Australia generally require two types of product, the first of which is the “fresh
cut” product. This type of product can be grown in either NFT or medium based systems, as
the leaves of the herbs are cut away from the roots for processing into sealed bags or
containers.
The second type of product commonly seen on the
Australian market today is “living plant” herbs. Here
the plant is grown in NFT and harvested whole with
the root system intact. The herbs are then placed into
a plastic bag with a small amount of water or nutrient,
and sold as a single unit. This method provides the
retailer with a significant increase in shelf life thus
reducing the wastage experienced with the fresh cut

4. herbs.
Commonly grown herbs in NFT are basil and coriander, and they seem to be particularly
suited to this method of production. Herbs such as thyme, marjoram and sage are often
grown in a medium based system, but can be grown just as well in NFT.
Most herbs can be grown in a variety of conditions and due to their relatively short lifespan,
can be grown with a good degree of success in most climates. They also grow very well on
the same system as lettuce, allowing a wider range of products to be marketed.
Growing herbs in NFT is one of the least physically demanding types of commercial
hydroponic production, and within reason, can usually be operated by a husband and wife
team.
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Lettuce
There are many different types of lettuce grown today which include all the different types of
lettuce normally sold in supermarkets throughout Australia and NZ. The method of growing is
nearly always NFT, which as with herbs, allows for the finished plants to be sold as either
“fresh cut” or “living plant”.
While the market for lettuce in the bigger cities may be
difficult to access, there are opportunities in regional
areas for smaller systems of say 1,000 to 1,500
square meters to meet the demand for ‘local’ fresh
produce. As with all commercial systems we can not
over emphasize the importance of establishing a
potential market first. Whether you develop a simple or
‘high tech’ commercial system, the exercise is
pointless if you have nowhere to sell your produce.
Romain or cos lettuce are currently very popular
amongst commercial hydroponic growers. Varieties
include; Red Romaine (tolerant to both heat and cold), Paris White, Parris Island, Cos Verdi,
Toledo, Marvel, Diamond Gem, and Little Gem to name a few.
Growing time for lettuce can be anywhere between 60 and 80 days, and these plants can
often be grown outdoors with relative ease in hotter climates. This of course can save quite a
lot money on the initial outlay for a commercial farm, and is one of the reasons that lettuce is
so popular with many commercial hydroponic growers. Another reason is the ability to grow
herbs such as basil and coriander alongside lettuce to increase the range of produce
provided by the grower.
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Ornamentals
There are currently many different types of ornamental
flowers under hydroponic production today, with some
of the most common being gerberas, carnations,
lisianthus, roses and chrysanthemums.
The main difference between ornamental crops and
food crops (apart from the obvious), is the level of
environmental control needed to achieve optimum

5. growth. The parameters for ornamental production are very rigid to say the least, and setup
costs can be daunting.
Another problem being faced by hydroponic ornamental growers is competition from abroad
in addition to the down turn in the tourism and hospitality industry. Careful consideration must
be given prior to venturing into the commercial flower industry, where a confirmed market is
essential. Also the threat of cheap ornamental imports from across the globe can mean that
a once solid and reliable outlet for your produce can suddenly be faced with the option of
reducing there costs considerably, and few retail sellers will be able to say no this sort of
incentive. After all, if they don’t take the flowers at a cheaper price then the shop next door
probably will, and they will lose business to them. With this in mind careful market research is
an absolute must for this type of start up, and the worst case scenario must be your starting
point.
Given the complexities in growing commercial ornamentals, a good alternative could be to
‘learn the ropes’ on a more forgiving hydroponic system such as herbs or lettuce, as there
always tend to be a good market in most regions. As your knowledge and capability increase
it may be possible to approach local ornamental retailers with some sample produce to see if
they are interested. In this way you have something to show the retailer when you do your
market research, in addition to having a good idea of your production costs (and therefore
your break even price), and by then you should know whether or not ornamental growing is
for you.
We don’t mean to sound negative on this subject, but it is no secret that at the moment
current market conditions in Australia for ornamental plants are a bit volatile, and new start
ups may experience significant difficulties in gaining a foothold into the market place. That
said, if you have a good market, we will of course happily consult on ornamental flower
production for you. Other crops include:-
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Other crops include :-
VINE CROPS BRASSICAS
Tomatoes (Lycopersicon lycopersicum) Broccoli (Brassica oleracea var. italica)
Capsicum (Capsicum annum) Cauliflower (Brassica oleracea var.
Cucumber (Cucumis sativa) botrytis)
Cabbage (Brassica oleracea var. capitata)
HERBS Rocket (Brassica rapa . var. chinensis)
Dill (Anethum graveolens) Kale (Brassica oleracea var. acephala)
Parsley (Petroselinum crispum)
Chives (Allium schoenoprasum) VEGETABLES
Mint (Mentha app.) Aubergine (Solanum melongena var.
Tarragon (Artemisia dranunculus) esculentum)
Marjoram (Maiorana hortensis) Carrots (Daucus carota)
Fennel (Foeniculum vulgare) Spinach (Spinacia oleracea)
Sorrel (Rumex acetosa) Asparagus (Asparagus officinalis)
Chicory (Cichorium intybus) Okra (Hibiscus esculentus)
LETTUCE ROOT VEGETABLES
Crisphead (Lactuca sativa var. capitata) Potato (Solanum tuberosums)
Butterhead (Lactuca sativa var. capitatis) Radish (Raphanus sativus)
Vietnamese (Lactuca sativa var. crispa) Onion (Allium cepa)
Romaine/Cos (Lactuca sativa var. Carrot (Daucus carota)
longifolia) Spring Onion (Allium fistulosum)
ASIAN VEGGIES SPICES

6. Amaranth (Amaranthus tricolour) Root Ginger (Zingiber Officionale)
Buffalo Spinach (Enydra fluctuans) Turmeric (Cucurma domestica)
Chinese Flowering Cabbage (Brassica Curry Leaves (Murraya koenigii)
rapa var. parachinensis)
Chinese Celery (Apium graveolens var. FRUIT
dulce) Watermelon (Citrullus lanatus)
Hot Mint (Poligonum minus)
Lemon Grass (Cymbopogon citratus)
Lizard’s Tail (Hottuynia cordata)
Mustard Green (Brassica juncea)
Pak Choi (Brassica rapa var. chinensis)
Pennywort (Centella asiatica)
Perilla (Perilla frutescens)
Thai Basil (Ocimum basilicum)
Spearmint (Mentha viridis)
Turmeric (Cucurma domestica)
Water Convolvulus (Ipomea aquatica)
Water Parsley (Oenanthe javanica)
Watercress (Rorippa nasturtium-
acquaticum)
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Our experience and expertise in the Hydroponics
market is unrivalled in Europe…”
Let’s talk about Commercial Hydroponics…
With many years of experience HydroGarden is the UK leader in hydroponics. We have
assisted many growers develop their businesses with our access to experts and consultants
in a wide range of topics including plant biochemistry, analytical chemistry, commercial
growers with crop specific knowledge, commercial installation experience and much more.
Several directors within HydroGarden have owned and operated their own commercial
hydroponic operations.
Hydroponics is also now recognised as an important research tool. It has particular
advantages where various controls are needed such as the pharmaceutical industry and
other areas of research where a clean root system is required for instance.
In Australia hydroponics production has risen from 155 hectares in 1990 to 500 hectares in
1996. This growth continues.
In progressive, forward thinking countries throughout the world the commercial hydroponics
industry has increased 4-5 fold during the last 10 years. It is currently estimated that the area
under hydroponic cultivation is between 20,000 and 25,000 hectares with a farm gate value
of US$6-8 billion.
HydroGarden believes that the future lies in locally grown and sold produce, limiting the ‘road
miles’ applied to today’s food supplies. Whilst export opportunities will occur, the main
development will be that smaller niche, locally based growers will sell to supermarkets,
farmers markets and wholesale operations as well as the consumer direct. This method of
growing our food is a more sustainable model than those currently practised. Today’s
consumer has become increasingly aware of health and environmental issues, even water
consumption and availability…these are all drivers for the further development of hydroponic
growing techniques.
As a company HydroGarden can assist you to identify the most suitable system for your

7. crop, location, skills and needs. We understand that different plants require different systems
in different locations and as such can offer those systems how and when you need them…
Why use Hydroponics?
There are 5 forces threatening long term crop and food production in open field situations:
1 Increasing ultraviolet radiation
2 Decreasing fresh water supplies and water quality
3 Increasing top soil erosion and soil degradation
4 Increasing resistance of insect pests and plant diseases to traditional chemical controls
5 A convergence of natural cycles leading to extreme weather conditions
Further, open field production is hindered because the grower has no control over the
growing environment. The result is that the grower cannot predict yields and is unable to
budget effectively. The field grower cannot always ensure adequate aeration of the rootzone
during periods of extended rainfall.
The results might be any of the following:
Anaerobic conditions will benefit the proliferation of fungus (Phytophthora sp.) and
nematodes that will attack the roots and eventually kill the plant.
Roots need oxygen to respire and therefore are not productive when the soil is saturated for
long periods.
Beneficial soil borne micro-organisms are eliminated, therefore exposing the roots to fungal
and bacterial attack.
Rain and excessive irrigation on the soil will leach essential nutrients from the root profile.
Nitrates can be washed through the soil profile and pollute streams, reservoirs and the sea.
Hydroponic nutrient solutions can be tailored to the plant requirements whereas in the field
there is a tendency to over or under-fertilise. Nutrients in the soil are often fixed as insoluble
compounds that are not available to plants and therefore a loss to the grower.
SOIL GROWN HYDROPONICALLY GROWN
Small plant - big root Big plant - small root
Looking at the benefits
Irrigation water in field grown operations cannot be effectively recycled. Hydroponics can
reduce irrigation water usage by 70% to 90% by recycling the run-off water. As water

8. becomes scarce and more important as a resource, the use of hydroponics and other water
saving technologies will increase.
Fungal disease can be significantly reduced through controlled humidity. Hydroponic
systems will reduce the amount of exposed moisture in the growing environment.
Hydroponics will effectively prevent wetting the leaf surfaces which, in normal agriculture,
provides the fungal spores with the perfect medium to proliferate.
All labour inputs associated with soil management, such as digging and weeding are
substantially reduced with hydroponics.
The use of Integrated Pest Management (IPM) in protected environments is ideally suited to
hydroponic growing techniques, especially when carried out in a protected environment such
as a glasshouse or plastic/polythene tunnels. The use of IPM can virtually eliminate the need
to use toxic and expensive chemical insecticides.
Taking all the above into account, it is easy to see why protected cropping in general and
hydroponics especially is becoming increasingly important.
A hydroponically grown greenhouse plant:
Can be protected from increasing and damaging UV radiation
Offers the possibility of safe biological control of insect pests and diseases
Uses water that is reclaimed and reused
Allows nutrients to be reclaimed, re-balanced and re-used
Can be protected from unpredictable weather patterns
Has a good root system that is at reduced risk from contaminants and diseases
Makes very efficient use of labour, which is increasingly expensive in western economies
Can be grown to take full advantage of their genetic potential and produce outstanding crops
by using optimum nutrient formulations
Can be producing at times when market prices are highest
Combine these factors with increasing public concern over food safety, pesticide residues
and fungicide use; it is easy to see that the future of crop production favours hydroponic and
greenhouse production. Especially when premium prices can be obtained and the demand is
sustainable.
Global diversity…
Lettuce, strawberries and cut flowers are well known commercial hydroponic crops in
Australia, and have been for the past decade and more. Tomatoes, pepper, cucumbers and
cut flowers form the bulk of Dutch hydroponic crops. A number of UK growers have
successful cucumber and tomato operations and many herb growers are moving into this
form of cultivation. Nowadays plants for essential oils, rare herbs, medicinal plants and
Chinese vegetables such as pak choi are more recent crops of great interest. There is a
developing interest in growing plants for pharmaceutical and nutraceutical use. It is possible
to grow practically any commercial crops hydroponically.
Commercial growers have been producing superbly flavoured hydroponic tomatoes for many
years. Speciality crops and even fruit trees can all be grown hydroponically.
We have recently learnt of a commercial hydroponic potato business in the Southern

9. Hemisphere !
We are seeing an increasing interest in the production of cut herbs and salad crops, driven
by the demand for convenience foods that are also seen as ‘healthy’.
The production of cut flowers is itself a huge market, the introduction of new more exotic
plant types lends itself to hydroponic production as a means of growing the best quality from
the outset and therefore making it more difficult for cheaper lower quality crops to compete.
We expect, in time, to see an increase in demand for edible flowers, especially for use in
restaurants and hotel complexes.
Even fruit trees can be grown this way. In fact there are very few plants that cannot be grown
hydroponically, the choice for a commercial operation is a pure economic one.
We produce a number of separate data sheets relating to various crop types and
opportunities, this information includes some basic plant growing information as well as
recommended or typical system types suitable for the crop. Whilst it is not exhaustive it will
give the reader an idea of the potential for hydroponic crop production.
Commercial systems…
All commercial systems are active, in that some form of pump or feeding device is used to
deliver fresh nutrient solution to the plants in an ongoing basis. These systems are more
productive and are therefore the only type suitable for commercial production.
Of the active systems available they break down into either re-circulating or run to waste; run
to waste systems are becoming less popular as environmental concerns and legislation
restricts, or even prohibits, nutrient run off. However, if the run off can be managed to obtain
a zero figure, these systems still have their place. As a company we encourage the use of re-
circulating systems to maximise resource utilisation, but this is not always possible in certain
circumstances. Re-circulating systems typically use one tenth of the water, a fraction of the
minerals and takes up from one third to one tenth the space consumed in traditional
agriculture.
There are a number of differing active systems available, but again these can be
easily categorised into:
Nutrient Film Technique (NFT)
Ebb & Flow (also referred to as Flood & Drain)
Drip Fed Media Based Culture
Aeroponics
Raft Type Systems
Nutrient Film Technique (NFT)
Nutrient Film Technique (NFT) is both simple to understand, operate and maintain. Plants are grown in equally spaced holes in plastic
gullys or formed plastic sheeting. A liquid nutrient solution of minerals and highly oxygenated water is pumped into the higher end of the
gully, gravity draws the nutrient past the plant roots and then back to the nutrient tank, where the process is repeated.
As the nutrient solution flows past the plants the roots are bathed in a thin nutrient rich film of solution that is ideally balanced in terms of
nutrition, oxygen, pH and strength. As this is an enclosed re-circulating active system it ensures maximum production combined with
resource conservation.
The absence of growing media in NFT systems reduces costs but ensures the need to use high quality pumps and calls for a reliable
power supply to those pumps. The plants will quickly wither and die if the system is left ‘dry’ during the heat of the day.
Drip Fed Media Based Culture
Often called ‘slab culture’, this is most popular form of commercial hydroponics in countries
such as Holland. The plants are grown in a medium, most often Rockwool but more recently
in CoCo Coir. However, sawdust and sand have been used in some instances!

10. Slab Culture tends to be used for longer-term crops such as tomatoes, cucumbers and
peppers where a larger root system develops. The advantage of slab culture is that only
intermittent feeding of the plants is required. Also, the media itself tends to hold a large
amount of nutrients that are then available to the plants as needed. Often run off is limited to
a small percentage to ensure adequate feeding, but excessive run off is both expensive and
environmentally undesirable. As in ‘Ebb & Flow’, the media can act as a buffer in case of
pump or electricity failure.
Ebb & FlowEbb & Flow (or Flood & Drain) is a system where a tray or bed of plants are
alternatively flooded and then drained with the required nutrient solution. The flooding of the
media or plants acts to purge the media of stale oxygen depleted air and then draws in fresh
oxygen rich air to the root-zone when the system drains back into the nutrient tank.
This system is more suitable for longer-term crops such as trees & cut flowers where larger
root masses are likely. Ebb & Flow systems always use some kind of media that can act as a
buffer in case of pumps or electricity failure. Also, because the system is less active than an
NFT system the management of the nutrient solution is often less onerous than
that of NFT.
Aeroponics
Aeroponics is a system where often no media is present at all and the roots of the plants are
misted with the nutrient solution in a chamber or other suitable space. The mist has to be of a
certain size (5 micron max) to maximise growth and the delivery of the mist is a problem in its
own right. Blockages can occur and high-pressure pumps are often needed, this makes
Aeroponics less suitable for commercial production. However, we are aware of Aeroponic
systems being used for research and in some
‘niche’ applications.
The lack of any media in Aeroponics and the subsequent lack of buffering can
be problematic, but Aeroponic is a fantastic system when clean, fresh roots are needed!
Raft Type Systems
Raft Type Systems are those where the plant being cultivated is ‘floated’ on top of the
nutrient tank. The roots dangle in the nutrient and take up feed as needed. A large amount of
water is generally needed for such systems and the need to oxygenate the solution is
paramount. It would be easy to ‘drown’ the plants if the oxygenation system failed. Raft
systems are generally regarded as a bit outdated, but do have their place in certain
circumstances.
They are often cheap to construct and can be run without the use of nutrient pumps as long
as oxygen is supplied to the system in suitable quantities.
Some concerns exist over the use of re-circulating systems and the potential danger of
spreading disease throughout the system if it manifests itself. However, in our experience
this danger can be greatly reduced and even eliminated through the use of nutrient
sterilisation, strict cleanliness regimes or beneficial bacteria being used.
All of the system types discussed usually utilise automatic dosing controllers to constantly
monitor and maintain the optimum nutrient strength and pH balance.
As a company, we can advise on all system types and the suitability of that system to an
individual case
.
Whatever system is most suitable for your operation, we can supply it.
For any new grower we are happy to provide a small trial system at a special price.
The cost of this system would be credited to the grower should a full size system be
purchased as a result of the trial.

11. Getting started…
It is most important when considering the possibility of growing hydroponically, whether on a
small or large scale, that you seek advice from a number of sources. Talk to potential
customers and fully research the business. We will assist where ever possible. Carry out
research before you start and plan to start small! Each market, each crop and every growing
situation is different. It will be necessary to gain an overall understanding of the business and
crop before any significant system expansion takes place.
Don’t rely on a single source when obtaining information on crop yields for a specific crop,
check local as well as national and government sources.
We recommend the grower starts off with a small trial system, we can advise and assist with
these too. A trial system enables the grower to get the hang of the basics of hydroponics. It is
easy, but you have to learn how to use it properly, how to get the correct balance of nutrients
for the correct flavour or colour and growth of the plant and how to recognise problems as
they arise.
Buy a good book. We sell several that are crop specific, and do some reading.
If possible visit an existing commercial grower - we may be able to help in providing contacts.
Ensure you perform adequate market research. Marketing is customer not product focussed.
If possible innovate to continuously improve product benefits. Try to add value as this will
attract new customers for your produce and ensure you keep existing ones.
There is much more to running a successful commercial operation than just growing high
quality produce. HydroGarden can advise on various ways to market your produce and how
to add value and with more general marketing advice.
Growing hydroponically will give you the ability to time harvests to match restricted
availability for certain crops, this aids in obtaining premium prices for the crop.
If necessary, we have the expertise in other business topics such as finance, which may also
assist.
By reading this brochure and by using the services offered, you will save time, effort and
money.
All under one roof…
Please refer to our Commercial Price List for the complete range of our products.
Not only can we provide the system, lighting and nutritional requirements for your system, we
also stock a large range of other essential items such as:
growing media
propagating products
low and high pressure pipe fittings
nutrient pumps
growth promoting and flowering additives
pH testing, adjustment and calibration products
nutrient testing and calibration products
nutrient sterilisation products
aeration products
monitoring and dosing equipment
filters and filtration products
plant support accessories to aid optimum growth
books
and more....
It is important to remember that all components used in a hydroponic system must be non-

12. toxic and must not react when exposed to the nutrient solution. This generally means plastic
or stainless steel materials.
Trial Systems
As a company we would always recommend that a new grower purchase a trial system in the
first instance. This will get you used to the techniques behind hydroponic cultivation and get
used to the control of the nutrient strength and pH
.
HydroGarden Trial System Offer!
We are always happy to deduct the cost of this initial trial system from the cost of any full
size system should you choose to purchase one. It all helps.
A helping hand
At Hydrogarden, we realise that a relationship starts, not ends, with a purchase of a system.
We are able to assist from the business or system planning stage, all the way through to on-
going grower support. We may even be able to help you buy or sell your business.
HydroGarden can assist you prior to starting growing with:
Water Analysis
Crop Specific Nutrients
Location Specific Nutrients
Location and Natural Environmental Considerations
Crop Considerations as well as Yield Forecasts and Predictions
System Layout, Specification and Considerations
Environmental Control and Protective Structural Considerations
Production Factors and Operating Costs
Management and Grower Considerations
Additional Resources that may be required
Supplementary Lighting Layout (if necessary)
Equipment Supply
Business Planning
Marketing Advice
Once the system is operational, we can advise, or obtain advice on:
Crop Specific Problems or Issues
Plant Tissue Analysis
Nutrient Analysis/Monitoring/Tissue Analysis and Nutrient Adjustment and Replenishment
Equipment Supply or Upgrades
Latest Technical Information and Innovations
Equipment Supply
Marketing Advice
Embracing the new…
Energy Conservation and Renewable Energy
We firmly support all initiatives to reduce unnecessary energy consumption in the projects we
are involved with. Where possible we will assist in lowering a grower’s dependence upon
fossil fuels.
The use of energy efficient glass or plastic structures, energy curtains, heat sinks, correct
design, location and layout, the correct use of ventilation and other initiatives can all assist in

13. making the project successful and sustainable.
The use of bio-fuels and other alternative sources of power such as micro-turbines can all
assist in making the commercial hydroponics industry a viable, long term one.
New Markets and Evolving Opportunities
Medicinal – Nutraceuticals – Cosmeceuticals – Pharmaceuticals – Essential Oils – Herbal
Medicines - Healthy Food – Safe Food – Farmers Markets – Localised Supply - Hydro-
0rganics - Utilisation of brown field sites - Urban Horticulture
Recent reports give reliable predictions that natural based products will penetrate the
synthetic pharmaceutical markets by up to 30% over the next 3 years (from 2003). Where will
these plant-based products be sourced? Nutraceuticals (foods that are beneficial to our
health) are also expected to maintain the growth seen over the past decade. A number of
these foods require plant-derived materials that are often found in a plant’s root zone. The
use of hydroponic growing methods alone can ensure the clean, controlled product that is
required. Pharmaceutical companies also need raw materials that are pesticide free, of high
quality and have been grown in a controlled method…sound familiar? They have to be grown
in controlled, clean environments such as hydroponics can provide. It is unlikely that this
growth in demand will be met by ravaging the already delicate eco-systems represented by
rainforests and similar natural resources.
In the USA it is common for high value foods to be grown hydro-organically, that is using
organic nutrients in a hydroponic system.
The demand for more natural based products is unlikely to diminish in the foreseeable future.
Combine these factors with the increasing interest in pesticide free, healthy, vitamin rich
foods and you can see why we are so excited about the future prospects of our industry…
In conclusion…
Over the past 9 years, HydroGarden has been actively involved in the global Hydroponics
industry and has gained a reputation for the supply of quality products at affordable prices.
Our experience and expertise in the Hydroponics market is unrivalled in Europe and we
know that commercial hydroponic systems are serious business. We have contacts with
hydroponic companies and commercial growers worldwide.
So if we do not know the answer we can find someone who does!
As well as designing, supplying and maintaining systems, HydroGarden staff and directors
have hands on experience of growing. This personal experience is something that few, if any
other, firms can claim. We know what it is like when the insects attack or the varieties are
wrong. We have also felt the joy of growing the best quality crops in the shortest possible
time!
If you are considering entering into hydroponics on a commercial basis, we invite you to talk
to us. Not only will you find our company friendly and efficient, our range of quality products
and backup is the best available anywhere.
HydroGarden will talk with you about the system you need, the returns you will require and
the obstacles you may encounter.
So, if you are after the right advice, equipment and system design, call us today on

14. +44 (0)24 7660 8080 +44 (0)24 7660 8080 FREE or fax us on +44 (0)24 7665 1060
You can also email us or visit our web site
rob.h@hydrogarden.co.uk
www.hydrogarden.com
Wikipedia Definition
Hydroponics is a subset of hydroculture and is a method of growing plants using mineral
nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in
the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool,
expanded clay or coconut husk.
Researchers discovered in the 18th century that plants absorb essential mineral nutrients as
inorganic ions in water. In natural conditions, soil acts as a mineral nutrient reservoir but the
soil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve in
water, plant roots are able to absorb them. When the required mineral nutrients are introduced
into a plant's water supply artificially, soil is no longer required for the plant to thrive. Almost
any terrestrial plant will grow with hydroponics. Hydroponics is also a standard technique in
biology research and teaching.

15. Contents
[hide]
• 1 History
• 2 Origin
o 2.1 Soilless culture
• 3 Advantages and disadvantages
o 3.1 Advantages
o 3.2 Disadvantages
• 4 Techniques
o 4.1 Static solution culture
o 4.2 Continuous-flow solution culture
o 4.3 Aeroponics
o 4.4 Passive sub-irrigation
o 4.5 Ebb and flow or flood and drain sub-irrigation
o 4.6 Run to waste
o 4.7 Deep water culture
o 4.8 Bubbleponics
o 4.9 Fogponics
o 4.10 Rotary
• 5 Substrates
o 5.1 Expanded clay aggregate
o 5.2 Growstones
o 5.3 Coir
o 5.4 Rice Hulls
o 5.5 Perlite
o 5.6 Pumice
o 5.7 Vermiculite
o 5.8 Sand
o 5.9 Gravel
o 5.10 Wood fibre
o 5.11 Sheep wool
o 5.12 Rock wool
o 5.13 Brick shards

16. [edit] History
Further information: Historical hydroculture
The earliest published work on growing terrestrial plants without soil was the 1627 book
Sylva Sylvarum by Francis Bacon, printed a year after his death. Water culture became a
popular research technique after that. In 1699, John Woodward published his water culture
experiments with spearmint. He found that plants in less-pure water sources grew better than
plants in distilled water. By 1842, a list of nine elements believed to be essential to plant
growth had been compiled, and the discoveries of the German botanists Julius von Sachs and
Wilhelm Knop, in the years 1859-65, resulted in a development of the technique of soilless
cultivation.[1] Growth of terrestrial plants without soil in mineral nutrient solutions was called
solution culture. It quickly became a standard research and teaching technique and is still
widely used today. Solution culture is now considered a type of hydroponics where there is no
inert medium.
In 1929, William Frederick Gericke of the University of California at Berkeley began publicly
promoting that solution culture be used for agricultural crop production.[2] He first termed it
aquaculture but later found that aquaculture was already applied to culture of aquatic
organisms. Gericke created a sensation by growing tomato vines twenty-five feet high in his
back yard in mineral nutrient solutions rather than soil.[3] By analogy with the ancient Greek
term for agriculture, geoponics, the science of cultivating the earth, Gericke coined the term
hydroponics in 1937 (although he asserts that the term was suggested by W. A. Setchell, of
the University of California) for the culture of plants in water (from the Greek hydro-,
"water", and ponos, "labour").[1]
Reports of Gericke's work and his claims that hydroponics would revolutionize plant
agriculture prompted a huge number of requests for further information. Gericke refused to
reveal his secrets claiming he had done the work at home on his own time. This refusal
eventually resulted in his leaving the University of California. In 1940, he wrote the book,
Complete Guide to Soilless Gardening.
Two other plant nutritionists at the University of California were asked to research Gericke's
claims. Dennis R. Hoagland[4] and Daniel I. Arnon[5] wrote a classic 1938 agricultural bulletin,
The Water Culture Method for Growing Plants Without Soil,[6] debunking the exaggerated
claims made about hydroponics. Hoagland and Arnon found that hydroponic crop yields were
no better than crop yields with good-quality soils. Crop yields were ultimately limited by
factors other than mineral nutrients, especially light. This research, however, overlooked the
fact that hydroponics has other advantages including the fact that the roots of the plant have
constant access to oxygen and that the plants have access to as much or as little water as they
need. This is important as one of the most common errors when growing is over- and under-
watering; and hydroponics prevents this from occurring as large amounts of water can be
made available to the plant and any water not used, drained away, recirculated, or actively
aerated, eliminating anoxic conditions, which drown root systems in soil. In soil, a grower
needs to be very experienced to know exactly how much water to feed the plant. Too much
and the plant will not be able to access oxygen; too little and the plant will lose the ability to
transport nutrients, which are typically moved into the roots while in solution. These two
researchers developed several formulas for mineral nutrient solutions, known as Hoagland
solution. Modified Hoagland solutions are still used today.
One of the early successes of hydroponics occurred on Wake Island, a rocky atoll in the
Pacific Ocean used as a refuelling stop for Pan American Airlines. Hydroponics was used
there in the 1930s to grow vegetables for the passengers. Hydroponics was a necessity on
Wake Island because there was no soil, and it was prohibitively expensive to airlift in fresh
vegetables.

17. In the 1960s, Allen Cooper of England developed the Nutrient film technique. The Land
Pavilion at Walt Disney World's EPCOT Center opened in 1982 and prominently features a
variety of hydroponic techniques. In recent decades, NASA has done extensive hydroponic
research for their Controlled Ecological Life Support System or CELSS. Hydroponics
intended to take place on Mars are using LED lighting to grow in different color spectrum
with much less heat.
[edit] Origin
[edit] Soilless culture
Gericke originally defined hydroponics as crop growth in mineral nutrient solutions.
Hydroponics is a subset of soilless culture. Many types of soilless culture do not use the
mineral nutrient solutions required for hydroponics.
Plants that are not traditionally grown in a climate would be possible to grow using a
controlled environment system like hydroponics. NASA has also looked to utilize
hydroponics in the space program. Ray Wheeler, plant physiologist at Kennedy Space
Center’s Space Life Science Lab, believes that hydroponics will create advances within space
travel. He terms this as a bioregenerative life support system.[7]
[edit] Advantages and disadvantages
This article contains a pro and con list. Please help improve it by integrating both sides into
a more neutral presentation. (November 2012)
[edit] Advantages
Some of the reasons why hydroponics is being adapted around the world for food production
are the following:
• No soil is needed for hydroponics
• The water stays in the system and can be reused - thus, lower water costs
• It is possible to control the nutrition levels in their entirety - thus, lower nutrition costs
• No nutrition pollution is released into the environment because of the controlled system
• Stable and high yields
• Pests and diseases are easier to get rid of than in soil because of the container's mobility
• It is easier to harvest
• No pesticide damage
• Plants grow healthier
• It is better for consumption
Today, hydroponics is an established branch of agronomy. Progress has been rapid, and
results obtained in various countries have proved it to be thoroughly practical and to have
very definite advantages over conventional methods of horticulture.

18. There are two chief merits of the soil-less cultivation of plants. First, hydroponics may
potentially produce much higher crop yields. Also, hydroponics can be used in places where
in-ground agriculture or gardening are not possible.
[edit] Disadvantages
Without soil as a buffer, any failure to the hydroponic system leads to rapid plant death. Other
disadvantages include pathogen attacks such as damp-off due to Verticillium wilt caused by
the high moisture levels associated with hydroponics and over watering of soil based plants.
Also, many hydroponic plants require different fertilizers and containment systems. [8]
[edit] Techniques
The two main types of hydroponics are solution culture and medium culture. Solution culture
does not use a solid medium for the roots, just the nutrient solution. The three main types of
solution cultures are static solution culture, continuous-flow solution culture and aeroponics.
The medium culture method has a solid medium for the roots and is named for the type of
medium, e.g., sand culture, gravel culture, or rockwool culture.
There are two main variations for each medium, sub-irrigation and top irrigation[specify]. For all
techniques, most hydroponic reservoirs are now built of plastic, but other materials have been
used including concrete, glass, metal, vegetable solids, and wood. The containers should
exclude light to prevent algae growth in the nutrient solution.
[edit] Static solution culture
In static solution culture, plants are grown in containers of nutrient solution, such as glass
Mason jars (typically, in-home applications), plastic buckets, tubs, or tanks. The solution is
usually gently aerated but may be un-aerated. If un-aerated, the solution level is kept low
enough that enough roots are above the solution so they get adequate oxygen. A hole is cut in
the lid of the reservoir for each plant. There can be one to many plants per reservoir.
Reservoir size can be increased as plant size increases. A home made system can be
constructed from plastic food containers or glass canning jars with aeration provided by an
aquarium pump, aquarium airline tubing and aquarium valves. Clear containers are covered
with aluminium foil, butcher paper, black plastic, or other material to exclude light, thus
helping to eliminate the formation of algae. The nutrient solution is changed either on a
schedule, such as once per week, or when the concentration drops below a certain level as
determined with an electrical conductivity meter. Whenever the solution is depleted below a
certain level, either water or fresh nutrient solution is added, A Mariotte's bottle, or a float
valve, can be used to automatically maintain the solution level. In raft solution culture, plants
are placed in a sheet of buoyant plastic that is floated on the surface of the nutrient solution.
That way, the solution level never drops below the roots.
[edit] Continuous-flow solution culture
In continuous-flow solution culture, the nutrient solution constantly flows past the roots. It is
much easier to automate than the static solution culture because sampling and adjustments to
the temperature and nutrient concentrations can be made in a large storage tank that has
potential to serve thousands of plants. A popular variation is the nutrient film technique or
NFT, whereby a very shallow stream of water containing all the dissolved nutrients required
for plant growth is recirculated past the bare roots of plants in a watertight thick root mat,
which develops in the bottom of the channel, has an upper surface that, although moist, is in
the air. Subsequent to this, an abundant supply of oxygen is provided to the roots of the
plants. A properly designed NFT system is based on using the right channel slope, the right

19. flow rate, and the right channel length. The main advantage of the NFT system over other
forms of hydroponics is that the plant roots are exposed to adequate supplies of water,
oxygen, and nutrients. In all other forms of production, there is a conflict between the supply
of these requirements, since excessive or deficient amounts of one results in an imbalance of
one or both of the others. NFT, because of its design, provides a system where all three
requirements for healthy plant growth can be met at the same time, provided that the simple
concept of NFT is always remembered and practised. The result of these advantages is that
higher yields of high-quality produce are obtained over an extended period of cropping. A
downside of NFT is that it has very little buffering against interruptions in the flow, e.g.,
power outages. But, overall, it is probably one of the more productive techniques.
The same design characteristics apply to all conventional NFT systems. While slopes along
channels of 1:100 have been recommended, in practice it is difficult to build a base for
channels that is sufficiently true to enable nutrient films to flow without ponding in locally
depressed areas. As a consequence, it is recommended that slopes of 1:30 to 1:40 are used.
This allows for minor irregularities in the surface, but, even with these slopes, ponding and
water logging may occur. The slope may be provided by the floor, or benches or racks may
hold the channels and provide the required slope. Both methods are used and depend on local
requirements, often determined by the site and crop requirements.
As a general guide, flow rates for each gully should be 1 liter per minute. At planting, rates
may be half this and the upper limit of 2 L/min appears about the maximum. Flow rates
beyond these extremes are often associated with nutritional problems. Depressed growth rates
of many crops have been observed when channels exceed 12 metres in length. On rapidly
growing crops, tests have indicated that, while oxygen levels remain adequate, nitrogen may
be depleted over the length of the gully. As a consequence, channel length should not exceed
10–15 metres. In situations where this is not possible, the reductions in growth can be
eliminated by placing another nutrient feed halfway along the gully and reducing flow rates to
1 L/min through each outlet.
[edit] Aeroponics
Main article: Aeroponics
Aeroponics is a system wherein roots are continuously or discontinuously kept in an
environment saturated with fine drops (a mist or aerosol) of nutrient solution. The method
requires no substrate and entails growing plants with their roots suspended in a deep air or
growth chamber with the roots periodically wetted with a fine mist of atomized nutrients.
Excellent aeration is the main advantage of aeroponics.
Aeroponic techniques have proved to be commercially successful for propagation, seed
germination, seed potato production, tomato production, leaf crops, and micro-greens.[9] Since
inventor Richard Stoner commercialized aeroponic technology in 1983, aeroponics has been
implemented as an alternative to water intensive hydroponic systems worldwide.[10] The
limitation of hydroponics is the fact that 1 kg of water can only hold 8 mg of air, no matter
whether aerators are utilized or not.
Another distinct advantage of aeroponics over hydroponics is that any species of plants can be
grown in a true aeroponic system because the micro environment of an aeroponic can be
finely controlled. The limitation of hydroponics is that only certain species of plants can
survive for so long in water before they become waterlogged. The advantage of aeroponics is
that suspended aeroponic plants receive 100% of the available oxygen and carbon dioxide to
the roots zone, stems, and leaves,[11] thus accelerating biomass growth and reducing rooting
times. NASA research has shown that aeroponically grown plants have an 80% increase in
dry weight biomass (essential minerals) compared to hydroponically grown plants.

20. Aeroponics used 65% less water than hydroponics. NASA also concluded that aeroponically
grown plants requires ¼ the nutrient input compared to hydroponics. Unlike hydroponically
grown plants, aeroponically grown plants will not suffer transplant shock when transplanted
to soil, and offers growers the ability to reduce the spread of disease and pathogens.
Aeroponics is also widely used in laboratory studies of plant physiology and plant pathology.
Aeroponic techniques have been given special attention from NASA since a mist is easier to
handle than a liquid in a zero gravity environment.
[edit] Passive sub-irrigation
Main article: Passive hydroponics
Passive sub-irrigation, also known as passive hydroponics or semi-hydroponics, is a method
wherein plants are grown in an inert porous medium that transports water and fertilizer to the
roots by capillary action from a separate reservoir as necessary, reducing labour and providing
a constant supply of water to the roots. In the simplest method, the pot sits in a shallow
solution of fertilizer and water or on a capillary mat saturated with nutrient solution. The
various hydroponic media available, such as expanded clay and coconut husk, contain more
air space than more traditional potting mixes, delivering increased oxygen to the roots, which
is important in epiphytic plants such as orchids and bromeliads, whose roots are exposed to
the air in nature. Additional advantages of passive hydroponics are the reduction of root rot
and the additional ambient humidity provided through evaporations.
[edit] Ebb and flow or flood and drain sub-irrigation
Main article: Ebb and flow
In its simplest form, there is a tray above a reservoir of nutrient solution. Either the tray is
filled with growing medium (clay granules being the most common) and planted directly or
pots of medium stand in the tray. At regular intervals, a simple timer causes a pump to fill the
upper tray with nutrient solution, after which the solution drains back down into the reservoir.
This keeps the medium regularly flushed with nutrients and air. Once the upper tray fills past
the drain stop, it begins recirculating the water until the timer turns the pump off, and the
water in the upper tray drains back into the reservoirs.
[edit] Run to waste
In a run to waste system, nutrient and water solution is periodically applied to the medium
surface. This may be done in its simplest form, by manually applying a nutrient-and-water
solution one or more times per day in a container of inert growing media, such as rockwool,
perlite, vermiculite, coco fibre, or sand. In a slightly more complex system, it is automated
with a delivery pump, a timer and irrigation tubing to deliver nutrient solution with a delivery
frequency that is governed by the key parameters of plant size, plant growing stage, climate,
substrate, and substrate conductivity, pH, and water content.
In a commercial setting, watering frequency is multi factorial and governed by computers or
PLCs.
Commercial hydroponics production of large plants like tomatoes, cucumber, and peppers use
one form or another of run to waste hydroponics.
In environmentally responsible uses, the nutrient rich waste is collected and processed
through an on site filtration system to be used many times, making the system very
productive.[12]

21. [edit] Deep water culture
Main article: Deep water culture
The hydroponic method of plant production by means of suspending the plant roots in a
solution of nutrient-rich, oxygenated water. Traditional methods favor the use of plastic
buckets and large containers with the plant contained in a net pot suspended from the centre
of the lid and the roots suspended in the nutrient solution. The solution is oxygen saturated
from an air pump combined with porous stones. With this method, the plants grow much
faster because of the high amount of oxygen that the roots receive.[13]
[edit] Bubbleponics
"Bubbleponics" is the art of delivering highly oxygenated nutrient solution direct to the root
zone of plants. While Deep Water Culture involves the plant roots hanging down into a
reservoir of water below, the term Bubbleponics describes a top-fed Deep Water Culture
(DWC) hydroponic system. In this method, the water is pumped from the reservoir up to the
roots (top feeding). The water is released over the plant's roots and then runs back into the
reservoir below in a constantly recirculating system. As with Deep Water Culture, there is an
airstone in the reservoir that pumps air into the water via a hose from outside the reservoir.
The airstone helps add oxygen to the water. Both the airstone and the water pump run 24
hours a day.
The biggest advantages with Bubbleponics over Deep Water Culture involve increased
growth during the first few weeks. With Deep Water Culture, there is a time where the roots
have not reached the water yet. With Bubbleponics, the roots get easy access to water from
the beginning and will grow to the reservoir below much more quickly than with a Deep
Water Culture system. Once the roots have reached the reservoir below, there is not a huge
advantage with Bubbleponics over Deep Water Culture. However, due to the quicker growth
in the beginning, a few weeks of grow time can be shaved off.[14]
[edit] Fogponics
Main article: Fogponics
Fogponics Fogponics is an advanced form of aeroponics which uses water in a vaporised form
to transfer nutrients and oxygen to enclosed suspended plant roots. Using the same general
idea behind aeroponics except fogponics uses a 5-10 micron mist within the rooting chamber
and as use for a foliar feeding mechanism.
[edit] Rotary
A rotary hydroponic garden is a style of commercial hydroponics created within a circular
frame which rotates continuously during the entire growth cycle of whatever plant is being
grown.
While system specific vary, systems typically rotate once per hour, giving a plant 24 full turns
within the circle each 24 hour period. Within the center of each rotary hydroponic garden is a
high intensity grow light, designed to simulate sunlight, often with the assistance of a
mechanized timer.
Each day, as the plants rotate, they are periodically watered with a hydroponic growth
solution to provide all nutrient necessary for robust growth. Due to the plants continuous fight
against gravity plants typically mature much more quickly than when grown in soil or other
traditional hydroponic growing systems. Due to the small foot print a rotary hydroponic

22. system has, it allows for more plant material to be grown per sq foot of floor space than other
traditional hydroponic systems.
[edit] Substrates
One of the most obvious decisions hydroponic farmers have to make is which medium they
should use. Different media are appropriate for different growing techniques.
[edit] Expanded clay aggregate
Main article: Expanded clay aggregate
Expanded clay pebbles.
Baked clay pellets, are suitable for hydroponic systems in which all nutrients are carefully
controlled in water solution. The clay pellets are inert, pH neutral and do not contain any
nutrient value.
The clay is formed into round pellets and fired in rotary kilns at 1,200 °C (2,190 °F). This
causes the clay to expand, like popcorn, and become porous. It is light in weight, and does not
compact over time. The shape of an individual pellet can be irregular or uniform depending
on brand and manufacturing process. The manufacturers consider expanded clay to be an
ecologically sustainable and re-usable growing medium because of its ability to be cleaned
and sterilized, typically by washing in solutions of white vinegar, chlorine bleach, or
hydrogen peroxide (H2O2), and rinsing completely.
Another view is that clay pebbles are best not re-used even when they are cleaned, due to root
growth that may enter the medium. Breaking open a clay pebble after a crop has been grown
will reveal this growth.
[edit] Growstones
Growstones, made from glass waste, have both more air and water retention space than perlite
and peat. This aggregate holds more water than parboiled rice hulls.[15]
[edit] Coir
Coco Peat, also known as coir or coco, is the leftover material after the fibres have been
removed from the outermost shell (bolster) of the coconut. Coir is a 100% natural grow and
flowering medium. Coconut Coir is colonized with trichoderma Fungi, which protects roots
and stimulates root growth. It is extremely difficult to over water coir due to its perfect air-to-
water ratio, plant roots thrive in this environment, coir has a high cation exchange, meaning it
can store unused minerals to be released to the plant as and when it requires it. Coir is

23. available in many forms, most common is coco peat, which has the appearance and texture of
soil but contains no mineral content.
[edit] Rice Hulls
Parboiled rice hulls (PBH) decay over time. Rice hulls allow drainage,[16] and even retain less
water than growstones.[15] A study showed that rice hulls didn't affect the effects of plant
growth regulators. [16] Rice hulls are an agricultural byproduct that would otherwise have little
use.
[edit] Perlite
Perlite is a volcanic rock that has been superheated into very lightweight expanded glass
pebbles. It is used loose or in plastic sleeves immersed in the water. It is also used in potting
soil mixes to decrease soil density. Perlite has similar properties and uses to vermiculite but,
in general, holds more air and less water. If not contained, it can float if flood and drain
feeding is used. It is a fusion of granite, obsidian, pumice and basalt. This volcanic rock is
naturally fused at high temperatures undergoing what is called "Fusionic Metamorphosis".
[edit] Pumice
Like perlite, pumice is a lightweight, mined volcanic rock that finds application in
hydroponics.
[edit] Vermiculite
Like perlite, vermiculite is a mineral that has been superheated until it has expanded into light
pebbles. Vermiculite holds more water than perlite and has a natural "wicking" property that
can draw water and nutrients in a passive hydroponic system. If too much water and not
enough air surrounds the plants roots, it is possible to gradually lower the medium's water-
retention capability by mixing in increasing quantities of perlite.
[edit] Sand
Sand is cheap and easily available. However, it is heavy, does not hold water very well, and it
must be sterilized between use.
[edit] Gravel
The same type that is used in aquariums, though any small gravel can be used, provided it is
washed first. Indeed, plants growing in a typical traditional gravel filter bed, with water
circulated using electric powerhead pumps, are in effect being grown using gravel
hydroponics. Gravel is inexpensive, easy to keep clean, drains well and will not become
waterlogged. However, it is also heavy, and, if the system does not provide continuous water,
the plant roots may dry out.
[edit] Wood fibre
Wood fibre, produced from steam friction of wood, is a very efficient organic substrate for
hydroponics. It has the advantage that it keeps its structure for a very long time. Wood fibre
has been shown to reduce the effects of "plant growth regulators."[16]

24. [edit] Sheep wool
Wool from shearing sheep is a little-used yet promising renewable growing medium. In a
study comparing wool with peat slabs, coconut fibre slabs, perlite and rockwool slabs to grow
cucumber plants, sheep wool had a greater air capacity of 70%, which decreased with use to a
comparable 43%, and water capacity that increased from 23% to 44% with use. Using sheep
wool resulted in the greatest yield out of the tested substrates, while application of a
biostimulator consisting of humic acid, lactic acid and Bacillus subtilis improved yields in all
substrates.[17]
[edit] Rock wool
Rock wool (mineral wool) is the most widely used medium in hydroponics. Rock wool is an
inert substrate suitable for both run to waste and recirculating systems. Rock wool is made
from molten rock, basalt or 'slag' that is spun into bundles of single filament fibres, and
bonded into a medium capable of capillary action, and is, in effect, protected from most
common microbiological degradation. Rock wool has many advantages and some
disadvantages. The latter being the possible skin irritancy (mechanical) whilst handling
(1:1000). Flushing with cold water usually brings relief. Advantages include its proven
efficiency and effectiveness as a commercial hydroponic substrate. Most of the rock wool
sold to date is a non-hazardous, non-carcinogenic material, falling under Note Q of the
European Union Classification Packaging and Labeling Regulation (CLP).[citation needed]
[edit] Brick shards
Brick shards have similar properties to gravel. They have the added disadvantages of possibly
altering the pH and requiring extra cleaning before reuse.
[edit] Polystyrene packing peanuts
Polystyrene packing peanuts are inexpensive, readily available, and have excellent drainage.
However, they can be too lightweight for some uses. They are used mainly in closed-tube
systems. Note that polystyrene peanuts must be used; biodegradable packing peanuts will
decompose into a sludge. Plants may absorb styrene and pass it to their consumers; this is a
possible health risk.
[edit] Nutrient solutions
Main article: Plant nutrition
Plant nutrients used in hydroponics are dissolved in the water and are mostly in inorganic and
ionic form. Primary among the dissolved cations (positively charged ions) are Ca2+ (calcium),
Mg2+ (magnesium), and K+ (potassium); the major nutrient anions in nutrient solutions are
NO−
3 (nitrate), SO2−
4 (sulfate), and H2PO−
4 (dihydrogen phosphate).
Numerous 'recipes' for hydroponic solutions are available. Many use different combinations
of chemicals to reach similar total final compositions. Commonly used chemicals for the
macronutrients include potassium nitrate, calcium nitrate, potassium phosphate, and
magnesium sulfate. Various micronutrients are typically added to hydroponic solutions to
supply essential elements; among them are Fe (iron), Mn (manganese), Cu (copper), Zn
(zinc), B (boron), Cl (chlorine), and Ni (nickel). Chelating agents are sometimes used to keep
Fe soluble. Many variations of the nutrient solutions used by Arnon and Hoagland (see above)

25. have been styled 'modified Hoagland solutions' and are widely used. Variation of different
mixes throughout the plant life-cycle, further optimizes its nutritional value.[18] Plants will
change the composition of the nutrient solutions upon contact by depleting specific nutrients
more rapidly than others, removing water from the solution, and altering the pH by excretion
of either acidity or alkalinity.[19] Care is required not to allow salt concentrations to become
too high, nutrients to become too depleted, or pH to wander far from the desired value.
Although pre-mixed concentrated nutrient solutions are generally purchased from commercial
nutrient manufacturers by hydroponic hobbyists and small commercial growers, several tools
exists to help anyone prepare their own solutions without extensive knowledge about
chemistry. The free and open source tools HydroBuddy[20] and HydroCal[21] have been created
by professional chemists to help any hydroponics grower prepare their own nutrient solutions.
The first program is available for Windows, Mac and Linux while the second one can be used
through a simple Java interface. Both programs allow for basic nutrient solution preparation
although HydroBuddy provides added functionality to use and save custom substances, save
formulations and predict electrical conductivity values.
The well-oxygenated and enlightened environment promotes the development of algae. It is
therefore necessary to wrap the tank with black film obscuring all light.
Organic hydroponics uses the solution containing microorganisms. In organic hydroponics,
organic fertilizer can be added in the hydroponic solution because microorganisms degrade
organic fertilizer into inorganic nutrients. In contrast, conventional hydroponics cannot use
organic fertilizer because organic compounds in the hydroponic solution show phytotoxic
effects.
[edit] Commercial
Some commercial installations use no pesticides or herbicides, preferring integrated pest
management techniques. There is often a price premium willingly paid by consumers for
produce that is labelled "organic". Some states in the USA require soil as an essential to
obtain organic certification. There are also overlapping and somewhat contradictory rules
established by the US Federal Government, so some food grown with hydroponics can be
certified organic.
Hydroponics also saves water; it uses as little as 1⁄20 the amount as a regular farm to produce
the same amount of food. The water table can be impacted by the water use and run-off of
chemicals from farms, but hydroponics may minimize impact as well as having the advantage
that water use and water returns are easier to measure. This can save the farmer money by
allowing reduced water use and the ability to measure consequences to the land around a
farm.
To increase plant growth, lighting systems such as metal-halide lamp for growing stage only
or high-pressure sodium for growing/flowering/blooming stage are used to lengthen the day
or to supplement natural sunshine if it is scarce. Metal halide emits more light in the blue
spectrum, making it ideal for plant growth but is harmful to unprotected skin and can cause
skin cancer. High-pressure sodium emits more light in the red spectrum, meaning that it is
best suited for supplementing natural sunshine and can be used throughout the growing cycle.
However, these lighting systems require large amounts of electricity to operate, making
efficiency and safety very critical.
The environment in a hydroponics greenhouse is tightly controlled for maximum efficiency,
and this new mindset is called soil-less/controlled-environment agriculture (CEA). With this

26. growers can make ultra-premium foods anywhere in the world, regardless of temperature and
growing seasons. Growers monitor the temperature, humidity, and pH level constantly.
Hydroponics have been used to enhance vegetables to provide more nutritional value. A
hydroponic farmer in Virginia has developed a calcium and potassium enriched head of
lettuce, scheduled to be widely available in April 2007. Grocers in test markets have said that
the lettuce sells "very well", and the farmers claim that their hydroponic lettuce uses 90% less
water than traditional soil farming.[22]
[edit] Advancements
With pest problems reduced, and nutrients constantly fed to the roots, productivity in
hydroponics is high, although plant growth can be limited by the low levels of carbon dioxide
in the atmosphere, or limited light exposure. To increase yield further, some sealed
greenhouses inject carbon dioxide into their environment to help growth (CO2 enrichment),
add lights to lengthen the day, or control vegetative growth, etc.