Tips for Growing Cabbage from A Greener View by Jeff Rugg

Tips for Growing Cabbage

Q: We planted a lot of cabbage this spring and didn't get around to harvesting all of it. It seemed fine, but recently we realized some of the heads have split in half, while others have new heads sprouting out of the middle of the old head. If that isn't bad enough, we harvested a head and found many of the inside leaves had dead and dried edges. This is making a lot of work to clean up before preparing for food. What can we do to prevent these problems next summer?
A: Cabbage plants are known as cool season plants because they grow better in the cooler times of the year. Also, they are biennials, which means they take two years to go through their life cycle. The first year, they produce a head, and after a cold dormancy period, they produce a tall flower stalk in a process called bolting.
Cabbage planted in the spring finishes producing a head in the summer, which is OK if you harvest it then. If you let the plant mature in warm weather, you may get the symptoms you mentioned. Fall planted cabbage plants tend not to split.

When the head is firm and solid, you should harvest it. If you don't, eventually the plant is going to take in more water. After it rains or when you water the plants, the plants will take in a bunch of water and may begin growing. The additional water and growth will create pressure on the existing leaves in the head, causing the head to split open. You can still harvest and eat the split head, but it also has a much greater chance of rotting before you get to it.
Some varieties split less than others and some split later in the season, so you can have a longer harvesting time. You can plant your cabbage plants over several weeks (even if you buy them all at once), so they don't all need harvesting at once. When you have too many plants to harvest at the same time, use a shovel to slice one or two sides of the cabbage plant; it will have a harder time getting water out of the ground.
You can also give the plant a slight twist to break some roots. Or use a knife to slice into the stem under the head. Too much nitrogen fertilizer can cause the head to expand rapidly and split. If the plant goes through a long enough dry dormancy or if cool weather hits after the summer weather, the plant may think it's in a second spring and begin to bolt. The flower stalk may develop leaves that look like another head is sprouting, but it may just be the flower stalk. Again, you can eat the existing leaves on the head, but you need to harvest it quickly before it bolts.
Fall planted cabbage heads can be left in the garden and harvested during the winter depending on where you live, but by next spring, you need to harvest the heads before the weather warms up and the plant bolts.
The dead leaves could be caused by a few different things. If you applied insecticidal soap for caterpillars, it can sometimes damage the leaves. As new ones form, the damage leaves should get pushed to the outside away from the head.
Damaged leaves within the head can be caused by inconsistent watering. The plant has a hard time getting calcium to the leaves when the soil moisture is going from one extreme to the other. This is the same cause for blossom end rot in tomatoes and other vegetables. Be consistent in your watering, and add mulch around the plants to slow the drying out of the soil.
Harvest the cabbage plant by cutting the head off and leaving the rest of the stalk with the old leaves. You will often get new heads developing at the base of the old remaining leaves. They will be small, but they will mature into the cool fall weather. There will be fewer caterpillars, and you should get some nice small heads to harvest.
E-mail questions to Jeff Rugg, University of Illinois Extension at jrugg@illinois.edu. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.
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