Brassicas - The Manual of Seed Saving - page 37

Brussels sprouts convar. fruticosa var. gemmifera

kale convar. acephala var. sabellica

collard greens convar. acephala var. medullosa

POLLINATION NOTES Cole crops are primarily pollinated by insects: honeybees, hoverflies, and
houseflies visit their sulfur-yellow flowers. Multiple varieties of the same crop or multiple cole crops
grown for seed in the same year must be isolated to avoid cross-pollination. Well-pollinated cole crops
can, in a good year, yield many thousand seeds, so it is worth it to pay close attention to your crop for
its entire life span. Seeds maintain reasonable viability for four to five years and individual (well-
ripened, well-stored) seeds may last up to 10 years.

GROWING FOR SEED Plant out heads of cabbage, kohlrabi, or other cole crops that produce seed the
second year in the spring when the soil is workable (early to mid spring). If it is too cold in spring to
plant out but plants are beginning to come out of dormancy, plant out in containers in a well-lit but
cool place. Harden off before planting out. When planting out, set plants deeper than they were in au-
tumn when they were dug up. The “neck” of cabbage, for example, should be entirely underground,
such that the head sits on the ground. This helps the plant develop new roots. Water plants well when
planting out and as they develop new roots. Some varieties send up seed stalks as high as 6 ft. (2 m)
and need plenty of space, optimally 24 by 24 in. (60 by 60 cm). Support each individual plant and, as
they emerge, the seed stalks, as they can become too heavy for the plant to support once seeds have de-
veloped. The largest, most viable seed comes from the central stalk; be sure this stalk develops well,
pruning weaker side growth if necessary, so the plant can concentrate its energy on developing good
seeds on the central stalk.

HARVEST Seeds are ready for harvest when the pods turn golden brown, usually mid to late summer.
If individual stalks ripen at different rates (which is often the case, especially if there are many side
stalks present), harvest entire individual stalks as they become ripe to avoid older seed dropping to the
ground when seedpods burst open while waiting for other pods to ripen. If all pods are ripe at the same
time, cut all stalks from the plant at once. Hang harvested stalks in a cloth bag in a warm, dry room
with good air circulation (such as an attic, not in direct sun) to dry. Pods are ready for threshing when
they are easily breakable with your fingers and the seeds fall out. Thresh on a tarp or tightly woven
fabric by rubbing pods between the hands or with a flail on a soft underlay. For larger quantities, walk
on seedpods spread on a tarp. At Arche Noah, threshing in a cloth bag on a soft surface has been
highly successful, especially with smaller quantities of seed, where it is crucial to prevent losing seed.
Seeds that are not easily threshed are likely unripe and therefore of poor quality or not viable at all.
Winnow seed in sieves and in the wind (separate out smaller, poorly developed seeds at this time as
well). Dry seeds further after cleaning before putting into storage.
Exact labeling of harvested seed stalks and threshed seed is extremely important, as it is often im-
possible to tell seed from Brassica oleracea , B. rapa , and B. napus crops apart. There is one trick that
may help, though, if seeds do get mixed up: when wet, B. oleracea seeds feel slimy, seeds of other
brassica species do not.