Seed Saving Biennials; by David Cavagnaro

1. Seed-Saving Biennials
by David Cavagnaro
I’ve been harvesting seed from all sorts of veg- of biennial crops from my home garden: cabbages,
etables since I was a kid growing up in northern kale, Brussels sprouts, leeks, beets, chard, carrots,
California. In a benign climate such as we had there, rutabagas, turnips. Once you understand the basic
getting a seed crop from your vegetables happens premise – you want to keep the plant in a dormant
almost on its own. Leave a plant – lettuce, broccoli, state, either indoors or in the garden, through the
Swiss chard, almost anything – in the ground just a winter and then grow it on the following spring until
little too long and pretty soon it’s going to seed. I it sets seed – the techniques aren’t difficult, they just
never bought seed unless there was a new variety that take a bit more time.
I was after. Maintaining my family’s supply of biennial seed
No matter where you live, it’s easy to save seed has become part of our routine for storing our winter
of annuals like tomatoes, peppers, lettuce, melons and vegetables. At harvest time we simply separate out
squash. And in zone 8 and southward, biennial crops some of the finer specimens as parent stock. We’re
– the cabbage family, onions and most root crops lucky to have a large root cellar, where the tempera-
– are easy too. But where winters are cold enough to ture averages 32 to 40°F and the humidity about 90%
freeze the ground hard, the biennials take a little more – the cole and root crops keep very well. Early the
effort. A lot of people, even committed seed-savers, following season we replant them outdoors, where
are unnecessarily afraid of trying. they quickly go to seed. Since seed for most of these
Today I live in zone 4, where the winters get to vegetables will keep five or six years, I only need to
30 below. And I’m still saving seed from all sorts do this for a handful of crops each year.
Brassica oleracea varieties
Many members of the family Brassicaceae are
annuals – mustards, Chinese cabbage, arugula, cress
and others – but members of the species oleracea are
biennials. Firm types of brassicas – kohlrabi, Brussels
sprouts and the hard storage varieties of cabbage – are
the easiest to save. The leafy brassicas (kale, collards
and Savoy cabbage) tend to mold and rot. Broccoli
and cauliflower behave like annuals. I’ll talk first about
cabbage because the way I handle any other brassica is
just a variation of the treatment I give cabbages.
I like to get my storage cabbages dug up and
in pots in the root cellar before the temperature ap-
proaches 20°F. I leave some cabbages in the garden
later than that for eating (throwing blankets or other
protection over them at night), but vegetables for the
root cellar must be in excellent condition. Cold-dam-
aged cabbages won’t last long before rotting.
Cabbages don’t have extensive roots. After
removing outer leaves, leaving just the heads, I lift
the plants with a shovel, shake off the dirt and place
them in five-gallon nursery containers, cramming
about five cabbages into each pot. I fill the contain-
ers with soil or sand and water well. The heads stay
absolutely perfect this way for seven or eight months.
Sometimes the humidity causes the outer leaves to
Root Cellar with Biennials for Seed Saving
rot. I just pull those leaves off and there’s a perfect
(Photo by David Cavagnaro)
cabbage underneath.
48 Seed Savers Exchange

2. Root crops
Carrots, beets, rutabagas, turnips and celery root
are not close relatives but are all brought through the
winter in a similar way. In mild climates they can be
left in the garden, perhaps with a little mulch to pro-
tect from cold where freezes do not penetrate deeply.
Where the ground freezes, it’s safest to dig them, trim
the leaves and store them in sawdust.
Parsnips are the only root crop that can survive
deep freezing. Even here in zone 4, I can leave them in
the ground without mulching. The only danger is from
voles, which can ruin root crops under mulch or snow.
Preparing Cabbages for Winter Storage I dig root crops for storage any time before the
(Photo by David Cavagnaro) ground freezes, though it can be a hand-numbing job
if the weather is very cold. I trim the leaves about a
With cabbages you can have your cake and eat it, quarter inch above the root, brush off the dirt and layer
too. All you need to plant out in the spring is the root the roots in wooden boxes.
with some stem – there are plenty of dormant buds Traditionally, sand is used to separate the lay-
along the stem that will sprout and go to seed. (Eat ers of root vegetables. But sand is heavy, so I prefer
the seed cabbage heads last, though, because once the coarse sawdust or even the chipped leaves I use for
head is cut off, the stem is far more prone to rotting.) mulch. Separate each root from its neighbor because
If you plant out a cabbage with the head still intact, some will inevitably rot (the separation keeps the
cut an X in the top to make it easier for the flower decay from spreading through the whole box). Start
stalk to emerge. with a fresh batch of packing material each season.
For loose-headed cabbages (early varieties. Sa- As with the cabbage family, select the best speci-
voys and collards), make a special planting for the mens for seed parents while you are sorting the crop for
seed crop, timed so you’ll have small plants with little packing. Seed stock should go in separate boxes that
heads when killing cold arrives. Dig the plants, strip are set aside, so there is no chance of eating them acci-
all the leaves until only a head about the size of a ten- dentally. Any roots with insects holes or other damage
nis ball remains, and pot them up for storage like the are most prone to decay and should be eaten first.
others. A late summer planting of kale overwinters All of these vegetables need cross-pollination so
right in the garden under a layer of mulch if winter you’ll need to plant at least two of each to get seed.
temperatures are not too severe. But keep in mind that many more, perhaps at least 20,
One cabbage will give you plenty of seed. Every- are necessary to maintain long-term genetic integrity
thing in this family needs cross pollination by insects, of these crops. Since these plants are much smaller
however, so you’ll need at least two to get a crop and than mature brassicas, a full patch does not take too
you must separate each cabbage variety from all other much garden space.
cabbages as well as any other brassicas. However, Beets are wind pollinated and will cross with
it takes far more than just two plants to maintain Swiss chard. The others are insect pollinated. Carrots
genetic viability in these biennial crops. Geneticists will cross with the Queen Anne’s lace, but the gene
recommend a minimum of 20 plants of vegetables like for white roots is dominant, so any orange carrot you
onions, leeks, or brassicas. That may be more than get the following season is sure to be true to variety
most backyard gardeners have space for. If so, you type. Other root vegetables will cross within the group
can save seed for a generation or two (in other words, as well as with wild relatives.
one or two times) before the genetic quality begins to Again, the easiest way to handle the problem is to
slip, then buy in fresh seed. grow just one from each group in a given year. Most
In the home garden, it’s easier just to save seed of these seeds will keep four years or longer with
from one brassica type each year and not worry about little trouble. The exception is parsnip seed, which is
separation distance. The seed will last four years or notoriously short-lived. We like parsnips, and I renew
more if kept dry at about 50°F. I routinely get five or the seed each year, which is as simple as leaving a few
six years out of mine. plants in the ground.
Russian kale is not a true kale; it is actually related To cover any storage losses, I like to reserve six
to rutabaga, Brassica napus, and will therefore not to a dozen of each root vegetable for the seed crop, but
cross with other kales or oleracea varieties. again, if you plan to maintain your seed stock through
2008 Harvest Edition 49

3. several generations, up that number to about two dozen. let the plants go to seed. For most varieties and best
All can be replanted outdoors as soon as the ground insurance of success, I dig leeks in the fall and replant
thaws in spring, set very close together in the row. them densely, as many as I can fit, if five gallon plastic
pots for root cellar storage.
Onions I dig up my red onions in the fall and sort them
Leeks are one of the easiest biennials to save be- for storage like the other crops, saving the very best
cause: most are so very cold hardy. But regular onions 20 or so for the seed crop. In mild areas you could
are one of the more difficult vegetables – it’s hard to replant the best specimens immediately and protect
bring them through a long winter in a fully dormant with a light mulch of leaves or straw. In our climate
state. Onion seed loses viability very quickly and where the ground freezes solid, onions tend to rot
you need to plant a good number of parents to keep even if mulched, so we have to bring them indoors.
the seed stock from gradually declining in quality. They will keep in a cold room (32 to 45°F) at 60 to
My family’s heirloom red onion kept getting smaller 70% humidity up to six months. They also keep well
and smaller and producing more multiple-centered under very warm conditions – 77 to 95°F and about
bulbs, until I learned to have 20 or more parents in 65% humidity.
my seed patch. My onions sprout in late January or February. I
Let’s start with leeks. In moderate climates you pot them up so they can grow roots and move them
can overwinter any leek outdoors with a bit of protec- into the root cellar. That tides them over until it’s safe
tive mulch. Here I can only overwinter the hardiest to move them outdoors. Onion varieties will cross-
varieties, which are generally the short, stocky ones. pollinate with each other as well as with shallots and
I dig them up and replant them in a trench at an angle, potato onions.
so the roots and growing tips are well protected with a For seed to remain viable a long time it’s crucial
bank of soil and only the tops of the leaves are above that it be completely dry. Cut the partially dry plants
ground. Then I cover the leeks with a thick blanket bearing the seed crop and move them indoors to a
of leaves. In spring, I just peel back the leaves and very dry room. Harvest seed just as it’s ready to fall
away from the parent plant or as the pods are about
to split. If the seed still feels slightly damp, spread it
on paper in a thin layer.
Store the seed in small paper envelopes labeled
with the name of the plant, the variety and the date.
The only truly airtight containers are metal or glass
with rubber gaskets on the lids. Many small paper
packets will fit into a large-mouthed glass jar. Weigh
the seed in the packets, then put them in the jar with
an equal weight of silica gel, which turns from blue
to pink as it absorbs moisture.
After a week in the container, the silica gel should
be removed (it can be dried out slowly in an oven
or microwave and reused many times) and the jar
promptly resealed. Seed treated this way will retain
excellent viability for a long time. If the glass or metal
container is kept in a refrigerator or freezer, seed life
is even longer.
I encourage every gardener in mild climates to
give biennial seed-saving a try. For those of us who
brave our more northern arctic winters, creating some
sort of cold but not frozen winter storage space is
necessary, following the same conditions needed for
good winter-long root crop storage.
David Cavagnaro is one of SSE’s advisors. He
Preparing Leeks for Root Cellar Storage spent eight years as the Garden Manager at Heri-
(Photo by David Cavagnaro) tage Farm.
50 Seed Savers Exchange