This document discusses temperature and shade regulation in greenhouses. It explains that leaf temperature is controlled by transpiration, while air movement also has a cooling effect. Effective ventilation is important, including ridge vents, doors, and side vents. Shade is also important and can be provided through external or internal blinds, shade cloth, or shading paints applied to the outside of the glass. Proper temperature and shade regulation is necessary to prevent plant damage and allow for optimal growth.

1. UHS BAGALKOT , COH BENGALURU
BY:
• ABEER ALI
• UHS16UG3006
• 3RD BSC HORTI
FLORICULTURE PRESENTATION

3. •Leaf temperature is mainly controlled by movement
of water through the plant and out through the leaf
surfaces in the form of transpiration – this process
has a cooling effect on the leaves.
•Air movement is the second important factor, air
movement over the leaf surfaces also has a cooling
effect.
TEMPRATUTRE REGULATION IN GREEN
HOUSE

4. Ventilation
•The door (either single or double doors)
•The roof vents (sometimes running the full length of the ridge
and opened either manually or with automated openers)
•The side vents (often lowered)
With larger glasshouses, one square meter of ridge ventilation
for each five square meters (20%) of floor area provides the
ventilating capacity to give one complete change of air within
the greenhouses every two minutes.

5. should ideally have an even higher percentage of ridge
ventilation. Unfortunately, this is seldom provided and amateur
greenhouses are very vulnerable to overheating.
Extra shading is commonly needed which can cut down on light
falling on the plants to a degree which reduces growth and
cropping.
Thankfully, the door of small greenhouses offers an alternative
means of ventilation which partially compensates for lack of
roof ventilation.
Side ventilation, commonly by lowers, is less effective than roof
vents

6. For effective ventilation:
•Monitor greenhouse temperature with a maximum-minimum
thermometer. If temperatures are allowed to build up
(typically more than 27°C/81°F) plant damage can occur
•Be alert for signs that shading and ventilation are required;
sun-flag (partial collapse), leaf scorch, desiccation of tender
young plants and shoots
•Open all doors and vents on sunny days. These can be left
open at night if the temperature remains high
•It is sometimes necessary to temporarily remove panes from
glasshouses to assist ventilation in heat waves

7. •Fit automatic vent openers to ensure roof vents open even
when you are not around. However, remember that since
they work by the expansion of wax in a cylinder to open the
vents, it takes time for the wax to expand. Provide plenty of
alternative ventilation (i.E. Doors and side vents) to prevent
damaging temperatures occurring before the openers respond
•In changeable weather, vents and doors often have to be left
partially open to limit sudden increases in temperature.
Larger greenhouses may, at high cost, be fitted with
automated ventilation and shading

8. •Open vent above door.
• Open side walls.
•Irrigate seedlings .
• white shade is more effective than other colours.
• Paint plastic with “whitewash” regulate interior
temperature
IT CAN BE ACHIEVED BY:

9. OPEN VENT ABOVE DOOR.
Roof and side vents on
conventional
greenhouses need to be
large enough to get
good air movement.

10. OPEN SIDE WALLS

11. IRRIGATE SEEDLINGS

12. WHITE SHADES

13. WHITEWASH THE PLASTIC

14. SHADE REGULATION IN GREEN HOUSE•Shading is usually required from mid-spring until early
autumn.
•Unfortunately, shading limits the light plants receive. As
plant growth depends on light, only the minimum amount of
shading should be used to keep temperatures below about
25-27ºc (77-81ºf). Otherwise, allow as much light in as
possible, particularly when growing edible plants such as
tomatoes. There is often no need to shade sun-loving plants
such as succulents although the greenhouse is more pleasant
to be in when shade is provided.

15. •External blinds: give shade and also provide the maximum
cooling effect by preventing the sun's rays from passing
through the glass. In periods of dull weather they can be easily
drawn up again to allow maximum light on to plants. However,
they are likely to be one of the more expensive options (and
may interfere with vents).
•Internal blinds: do not have the same cooling effect as
external blinds since sunlight is allowed to pass through the
glass and generates heat. However, they are probably more
easily automated than external blinds in order to provide
shade when it is most required. There are a wide variety of
materials available in a range of degrees of shading and with
varying permeability to allow air exchange

16. inside the glasshouse and fixed with clips. External fitting is
better but harder to arrange. This is a cheaper option than
blinds. The plastic is likely to biodegrade over a number of
years but is not expensive to replace.
•Shading paints: are diluted in water and painted onto the
outside of the glass in spring. Examples include sunclear,
varishade and nixol. As the season progresses, thicker
applications can be applied. In early autumn the coating
is washed and brushed off. Shade paints are less suitable for
unpainted timber structures that are left as natural wood and
for structures glazed with acrylic or polycarbonate because
even thorough cleansing may fail to remove all visible traces
of the shading paints. Some paints are designed to become
translucent when wetted.

17. THANK YOU……!