Some of the agricultural species of brassica today include: rutabaga, turnip, kohlrabi, cabbage, kale, broccoli, cauliflower, Brussels sprouts, mustard, cress, bok choy, and rapeseed (or, in the U.S., canola).
The brassicas provide high levels of nutrients, including Vitamin C, soluble fiber, and several anticancer agents. To maximize the nutritional value of these plants avoid boiling them, and instead steam them for 3-4 minutes.
The ten most commonly eaten cruciferous vegetables are in a single species B. Oleracea, and only differ by cultivar. Check out the Taxonomy Chart at Wikipedia to see just how closely related these plants are.
What follows is a brief description of the culture of the cole crops I am most familiar with:
Broccoli was first introduced to the United States by Italian immigrants but did not become widely known until the 1920s.
Broccoli: broccoli is an annual, it will sprout from seed, grow, flower, and seed all within one year. Like most of the popular cole crops, broccoli can be over-wintered in a sunny spot with a mild climate. Light frost will not harm it, and in fact, too warm temperatures in Spring and Summer may cause it to bolt, going from dense green (or purple) heads to yellow flowers nearly overnight. Once broccoli heads begin to flower they become very bitter. Plants grow in an upright manner, unlike their cousins the cabbages. Seeds can be started as early as December indoors, then planted outside once soil temperatures reach 50 degrees. The earlier broccoli is transplanted, the better, as it will be more likely to produce large heads before the weather warms too much. Broccoli can be planted as a Spring crop or direct seeded in summer for a Fall crop. It prefers cool, moist soil; it is not susceptible to molds for the most part. The primary scourges of broccoli, and most other cole crops are slugs and cabbage moth caterpillars. Removing plants after harvest can reduce the damage of caterpillars, as can row covers early in the season (preventing moths from laying eggs), and keeping plants indoors until they have at least two sets of true leaves will help with slugs. Slugs
will eat holes in the leaves but if plants are large enough this is only cosmetic and won't affect the harvest.
|Imported Cabbageworm, A.K.A. Cabbage moth larva.|
Cauliflower: cauliflower is similar to broccoli in many ways, it is annual, prefers cool weather, is mostly disease-free, and shares the same pests. Cauliflower is usually planted early in Spring, or in the late summer for Fall harvest, along with its cousins broccoli and cabbage. Cauliflower tends to be more picky about heat and drying out though, I have heard many a gardener bemoan the cracking and loss of their cauliflower heads after dry spells. Planting early, even watering, or planting as a Fall crop are some ways to prevent this. To keep your cauliflower pearly white, you should blanch it by wrapping the leaves over the head as it begins to develop. Cauliflower most often is found as a tight packed white ball, but is also found in green, orange, and even purple. Check out the different tastes of these variations at a local farmer's market and ask what the varieties are called so you can plan to plant your favorite in Fall, or next Spring.
Cato the Elder praised the cabbage for its medicinal properties, declaring that "It is the cabbage that surpasses all other vegetables."
Cabbage: much like the previous two plants cabbage is grown in early Spring or late Summer. It prefers cool weather, has no real disease problems, and few pests. Cabbage however, is much less finicky when it comes time to harvest. Primarily this is because cabbage is a biennial, it won't flower or go to seed until its second year of growth. Because of this a head of cabbage can often be left for several weeks before it has to be harvested; it also means it is far less likely to split, and only extreme temperature or moisture changes will cause the head to split. Cabbage requires no blanching either. It is most commonly found as a solid green ball, but is also available in red or purple varieties, Chinese cabbage which is much looser leaved, and in all different sizes as well, from fist-sized to pumpkin-sized. Cabbage heads are ready to be harvested when they are solid and hard to the touch.
In addition to this, cabbages are one of the prettiest plants to grow in my opinion. I love the way their flat leaves open up into a massive rosette around the globe-like head. The blue-tinged leaves sometimes take on a purple tinge as well, all in all they are very pretty.
In square foot gardening, broccoli, cauliflower, and cabbage each take one square foot to grow. If you are selecting large varieties though it doesn't hurt to have nearby squares only half filled with smaller plants, such as 2 lettuce, or 4 peas. Cabbage leaves especially are very wide and can cover up other plants next to them if they are too close. One way to manage this is to grow cabbages in between slightly taller growing plants, the cabbage leaves can shade the roots of the taller varieties and in return they shade the cabbage a bit.
Saving seed from these crops can be a bit tricky, since the cultivated brassicas are so closely related they can easily cross-pollinate. A 3-4 year rotation of seed saving can help with this: Year 1, save broccoli seed, not allowing other annual brassicas to flower; Year 2, save cabbage seed from biennial cabbage planted the previous year, not allowing other brassicas to flower; Year 3, save seed from cauliflower, don't allow others to flower; Year 4, repeat with another biennial, or annual brassica. Since brassica seeds stay viable for 3 years this is a good rotation to follow, any more years would leave you with very old seed that may not germinate from your first year. If you have more than four brassica cultivars you will either have to resort to trading for or buying seed, or put plenty of space between your cultivars. There are other ways to manage this, including bagging, spacing farther apart, etc. but this is probably the simplest. No extra steps but harvesting everything you don't want seed from before it blooms.
A final note on these crops: although we normally eat only the heads of these three plants, the outer leaves and stems are edible as well. If you find yourself a bit short on cabbage for a recipe you can add cauliflower leaves, outer cabbage leaves, and broccoli leaves and stems (so long as they haven't become woody and tough) to fill in.
I think that's all I have for these crops, I will post some of my favorite recipes for them soon as well. If you have any other tips or tricks about cole culture to share please leave a comment!