“Why are my cabbages only growing big leaves and not forming heads?” this is a common question farmers have been asking in our feedback pages.
Today, I will address the issue. Cabbages produce lots of leaves after planting. But as they mature, the inner leaves at the centre of the crop begin to curl inwards to form a head. However, formation of the head can be affected by a number of reasons.
Give your cabbages enough space to grow. Do not plant cabbages too close together to allow them grow properly. Depending on the variety of cabbage, the space between plants and between rows may vary. Larger varieties will require more space than the dwarf ones. The ideal spacing ranges from 30-45 cm apart and 60 cm between rows. Pay attention to spacing recommendations on the seed packet.
2. High temperatures
Cabbages require cool temperatures to form a head. It is therefore important to plant them at the right time of the year so the head will have time to form when daytime temperatures are still below 27°C (80°F). If it gets too hot, plants may stop growing leaves and instead send up a flower stalk and go to seed.
3. Too much or too little Nitrogen
Too much fertiliser can lead to excess nitrogen, which will force the plant to produce attractive green leaves, possibly at the expense of head formation. Do not apply fertiliser during head formation stage, as this may cause excessive leaf growth and splitting of the head. In as much as excess nitrogen may cause poor head forming, a complete lack of or poor supply of fertiliser thereof will also lead to no head. Cabbages will do well with rich compost added to the growing medium at planting. Furthermore, compost fertiliser must be added every two weeks until the heads start forming.
4. Pest and disease damage
Cabbages like any other crop are prone to disease and pest. Diseases could be one of the reasons why your cabbages are not forming heads. Some disease symptoms are apparent immediately yet others remain hidden until it is too late. One such cabbage disease is Club root which attacks the roots. The roots are deformed ultimately destroying the plant. Cabbages infected with Club root will fail to form heads even under ideal conditions. Practice crop rotation to control diseases. Also, if the central growing point of a young cabbage plant is damaged by pests, the existing leaves in the middle of the plant will thicken and harden, and no additional leaf growth will be produced in that portion of the plant, preventing the formation of a head. For this reason, it’s important to protect young plants from pests.
5. Moisture stress
Cabbages require adequate moisture. Inconsistent moisture supply will result in poor texture, become excessively bitter, and may not form a head. Good quality heads of cabbage should be firm, crisp, juicy, and sweet, they may sometimes be peppery. Depending on rainfall, cabbages may need watering around 2-3 times a week. Too much water may cause the heads to split. Water the plants early in the morning, as this allows the leaves to dry out in the sun during the day, and helps prevent common fungal diseases. The use of mulch helps to control moisture loss from soils around your cabbages. Mulch is also useful in suppressing weeds that bring competition to your cabbages.