Growing cabbage and its friends

Broccoli, cabbage, Brussels sprouts, kale… they are all varieties of the same species, Brassica oleracea. So are cauliflower, collards, kohlrabi and gai lan, also known as Chinese broccoli. Mustard, turnip and bok choy are in the Brassica genus too, but they are not in the species oleracea. Does it matter? Not really, but it’s oleracea were talking about here.

Folks started cultivating wild cabbage, perhaps as long ago as 5000 years, and definitely by 2000 BCE. By selecting seed from those with the biggest leaves or stems or flowers, all these different sizes, colours and shapes of vegetable came to be.

Cabbages and their ilk can be grown anywhere with good, fertile soil, so long as there are enough frost-free days (or days with just a little frost) for them to reach maturity in the garden. Most like long days but prefer cooler summers and won’t do well when the thermometer goes above 26 degrees Celsius; they tend to bolt. How do they grow them in the hot US South? In fall, not in summer.

Although brassicas are cool-season crops, they need warm soil to germinate from seed. The solution a lot of gardeners use for all but kale and collards is to start plants indoors and transplant

Wild cabbage (above) has been bred into a wide range of cultivars, including broccoli, cabbage, brussel sprouts, kale, cauliflower, collards, kohlrabi and gai lan.

This family of vegetables has a shallow root system, so you need to keep the area weeded. Remove weeds by hand, not by hoe, to avoid damaging the roots. And, of course, keep it mulched.

When you plant them out in the early spring, consider a row cover or some other protection. This will keep a number of pests out and keep the temperature more consistent.

Water is of great importance. These vegetables like a lot of it and they like the same amount of it from day to day, until they’re getting ready for harvest. Planting cabbage and broccoli for the first time? It’s a good excuse to invest in soaker hoses for watering because brassicas would rather stay dry above their feet.

Also important is pH. Brassicas grow best around 6.8 or 7. If you don’t know what your soil pH is, pick up a test at the garden centre. It’ll be a fun experiment. Then amend your soil to suit. And while you’re at it, add plenty of compost because brassicas are heavy feeders.

Kale, collards, kohlrabi and gai lan

These are the easiest brassicas to grow. You can seed them directly into the soil and harvest in 60 days or less. For kale, collards and gai lan, harvest the leaves as needed, choosing the outer leaves first. Once you cut the innermost leaves the plant may stop producing. For kohlrabi, harvest when the bulb gets to be about the size of a tennis ball. Don’t wait too long because older plants have an unpleasant texture.

Broccoli

There is a critical point of 10 days while growing broccoli, during which if the heat goes and stays above 35 Celsius for 4 days the broccoli will have badly shaped heads. This critical point is between the vegetative phase, when the plant is gaining size, and the flower bud stage.

For your first harvest, cut the central head of broccoli low down on the stem. Smaller side shoots may grow from the leaf axils, so you can continue to harvest for a few weeks. Cut the broccoli when the little green beads are tight. Don’t worry if your broccoli isn’t so big as what you’d buy at the market. If the beads start to turn yellow, harvest right away.

Cauliflower

Cauliflower used to take even more work because you had to “blanch” it by tying the leaves over the head so that it would stay white. To avoid the chore, look for self-blanching cauliflower.

Depending on the cultivar you get, cauliflower can take up to 100 days from seed to harvest. It doesn’t care for sudden change, not in temperature, water or nutrition. Start with your planting site well fed. If you start plants indoors, which you should because it needs heat to germinate, harden seedlings off before planting them out.

In addition to the usual cabbagefamily problems, your white cauliflower may turn brown, which means it’s low in boron, or pink, which means it’s had too much sun or the temperature has fluctuated too much. Either is fine to eat, though.

Harvest your cauliflower when the heads are tight. If they start to open, they won’t get any bigger and should be harvested immediately. If it starts to look kind of coarse, it’s past ripe and should be pitched.

Cabbage

The ability to grow a perfect cabbage is a sign of vegetable-growing competence. Aside from various diseases and pests that afflict cabbage, it feeds heavily and requires soil with a pH between 6.5 and 7. Keep cabbages consistently well watered but do not over water.

A cabbage can look ready to harvest before it is ready. Squeeze the head, looking for firmness. If it isn’t firm, leave it to grow a little longer. Check it regularly; if it is over-mature, the head can split. It will also split if the plant gets too much water or food.

Cut the watering a week before you plan to harvest and give the heads a twist to break some of the roots. This will prevent splitting by slowing the water uptake. When it is time, cut the cabbage from the plant. If there is still growing time in the season, leave the plant in the ground; little cabbages

Harlequin bug (Bagrada hilaris) on pakchoi.

may grow around the leaves.

Brussels sprouts

Brussels sprouts take four months to go from seed to harvest. If you don’t have more than four months frost-free in your area, start Brussels sprouts indoors. Winnipeg and Calgary, for instance, can only count on four months without frost and Saskatoon, even less. With these warnings, though, Brussels sprouts will benefit from some light frost before harvest.

The sprouts mature from the bottom of the plant first. You can harvest these when they’re firm. Remove leaves, too, from low on the plant, when they start to yellow. As you harvest the lowest sprouts, more will grow and mature higher up on the plant. You can also cut the top of the plant off three weeks before you want to harvest them all. This will ripen up all the sprouts.

Pests and diseases

Aphids: These little bugs will line up on the stem of a plant and suck out the juices. Spray them off with a water jet from a hose. Pull up old plant material where aphids overwinter. Avoid spraying with soap to encourage ladybugs or lacewings, which feed on aphids, to set up camp. We have heard (but not tried) sprinkling flour in the area to lead the aphids to become constipated.

Flea beetles: They look like specks of dirt until they jump. Grow mustard around your vegetable garden to attract flea beetles away from your plants. Try white sticky traps around the garden to catch the beetles when they jump. Use row covers and rotate plantings year by year.

Harlequin bugs: Plant cleome flowers or mustard around the border to attract them away. Hand pick the bright orange and black bugs. Look on the leaf undersides for black- and white-striped, barrel-shaped eggs and destroy them.

Cabbage root maggots: Plants will start yellowing on the outer leaves and eventually look wilted. Row covers will keep the parent flies from laying their eggs on vegetables. Cabbage collars are another solution, placed around each plant. Encourage ground beetles by using mulch.

Cabbage worms: A caterpillar won’t crawl on your vegetables for the heck of it. Any there are chowing down. There are three different kinds, but all three are susceptible to the same treatments. Grow flowers nearby to keep the beneficial insect population high. Use row covers. Catch the adults that lay eggs with sticky yellow traps in mid-summer.

Cutworms: These guys live in the soil during the day and come out at night to cut young plants down at the base. Include perches nearby to encourage worm-eating birds to hang out. One cutworm can do a lot of damage. Grab a flashlight and look for them after dark.

Clubroot: If plants are growing fine then suddenly fail to thrive, dig one up and see if the roots have galls. This is clubroot, a soil-borne fungus. Add lime to the soil and rotate your crops. If it gets to be a serious problem, solarize the soil to get rid of the pathogen.

Yellows: Leaves start to yellow at the base, usually on one side of the plant, and continue up the plant, turning brown. It’s a fungus in the soil. Plant resistant varieties. Changing the pH of the soil won’t work.

Black rot: The margins of the leaves turn yellow first in a v-shaped pattern with this soil bacterium. Rotate crops, keeping brassicas out of this soil for three years. It can come in on infected seeds or seedlings or can infect plants by splash-back from the soil. Watering at the root level only is one way to prevent the disease, mulching is another. j

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Check out the Rocket Surgeons official video for The Broccoli Song.