Kale, Collards, Savoy, Brussels Sprouts; they are just cabbages I am told. All Brassica oleracea. Cauliflower, Kohlrabi, Gai lan and Broccoli are also the same species. Since they are all the same species, they are capable of cross pollination. Maintaining the purity of a variety of any of these vegetable kinds requires that there are no other members of B. oleracea in bloom at the same time in the same garden where insect pollinators can transfer pollen among different plants. However, because of self incompatibility, it is useful to have many plants of the cultivar that you wish to save pure seed of. Many seed-savers see the need to preserve a large enough gene pool for the variety, at least a dozen plants.
The star of our 2005 cabbage trials, this popular European Cabbage known as "January King" was perhaps the most beautiful specimen in our patch. It started to show color in late fall and by Thanksgiving the purple highlights were very well developed. It's traditionally a "spring" cabbage in Europe maturing in 165 days or so in the regions where winters are mild. We have to fine tune our planting/harvest schedule to maximize head size next year- but it certainly has potential in our climate!
The flavor of January King was terrific. Sweet and crisp. It would be nice to develop an earlier version of January King. Plant in mid summer for an after-frost harvest. Cold is often the catalyst that brings on the best flavors like kale, collards, cabbage and brussels sprouts. Tones down the harsher mustard flavors and adds some sweetness. Although we're not reluctant to use summer cabbages and young kales and collards from the garden, we can't wait for frosty weather to finish off the crucifers for harvest. Below freezing weather doesn't damage this group unless temperatures drop down into the teens and low twenty's. For a seed crop, moving the rooted mature plants into a root cellar for humid, cold storage protected from the kind of intense winter freezing/thawing cyclesthat will kill these plants is essential. Some cultivars will over-winter in the field if given some protective mulching. January King has wintered over with mulch here on Long Island.
After January King, other cabbages are just cabbages. This year we trialed about a dozen varieties of cabbage from Europe recommended by organic growers there- some did quite well in our gardens. Look for specific varieties that we will release as local seed crops are produced.
To produce seeds one must overwinter the first year's crop. Cabbages, brussels sprouts, kales and collards are biennial. Some varieties of cabbage and brussels sprouts don't make it through our winters so that a heavy leaf mulch or a protective plastic cold-frame like cover by mid December is necessary. Many brassica including cabbage and brussels sprouts send up a mass of flower stalks from the main stem.
Cabbages are not known from the wild, they are a product of human selection. Wild cabbages are collard like. In selecting the traits we find important such as a rock-hard head for kraut and slaw and most of all to provide an easy kind of food storage through the winter (head cabbages store well), we have made the cabbage dependent on us in order to survive. Cabbage breeders have turned this leafy vegetable into a gigantic terminal bud, the growing tip confined beneath overlapping bud scale leaves. Sometimes cabbage heads will soften on their own after winter in the field so that the stem can emerge from the top of the cabbage, sometimes the entire plant will rot though. It may be necessary to split the cabbage head so that the terminal bud at the heart of the head can emerge. And then, sometimes dormant buds along the short stem beneath the head sprout in spring. It takes a while for the flower stalks to emerge and flower (in late April) and another month or two to produce seed pods that turn brown with ripe seed. Use care to harvest the seed before the pods (siliques) shatter.