Cabbages, unlike many vegetables, are suited to cool weather conditions. They are hardy plants that can withstand frost -- although, if the cabbage heads absorb too much water and then the water freezes, the cabbage heads can split or rot. If you have planted cabbages and are concerned that they don't appear to have formed heads, there may be several reasons. Learn them to diagnose and save your cabbage plants.
Cabbages are plants that form part of the Brassica family. Other members include Broccoli, Cauliflower, brussels sprouts and the increasingly popular Bok Choi from China. There are many varieties and sizes of cabbage; the leaves on the cabbage head can be purple, red or, more commonly, various shades of green. Cabbage heads form from multiple leaves that wrap themselves around each other, often tightly, making a dense mass.
To get the best chance of a good cabbage head growing, plant in early spring or mid-fall, when the weather is cool. Cabbages don't like hot conditions, which stunt growth, making cabbage heads unlikely to form. If you planted your cabbages during the summer months, this may be a reason why the cabbages haven't formed heads. Cabbages like plenty of water, but it is essential that the soil is well drained, otherwise the roots can rot. Expect your cabbages to take about two to three months to mature, depending on the type of cabbage you plant.
Cabbage heads form in the center of the plants, protected by layers of open large leaves. If you find that you have tall stalks extending upward from the base of the plant with multiple small heads, similar to brussels sprouts, it means the cabbage has decided to accelerate its rate of growth and effectively bypassed the stage where the head forms. This could be because the plant has suffered a lack of water or too much heat. It could also be as a result of the lower cabbage head splitting, allowing new shoots to grow. Once this occurs, there's little you can do except try again another season.
Many people expect their cabbage plants to miraculously develop large heads in a matter of days. Don't get too concerned if all you initially see are large leaves. Cabbage plants produce many large outside leaves before the heads start to develop. The leaves give protection to the small head when it starts to form. Plenty of outer leaves usually mean a healthy cabbage plant. Also, the early stages of a cabbage head are often discernible only as a bunch of soft, small leaves. So don't worry; be patient. The leaves should form and tighten.