Cultivating cabbage (Part 1): Building the foundation for a high-yield crop

Cabbage, one of South Africa’s most widely cultivated and consumed vegetables, offers farmers a reliable crop with strong market demand. Although it is relatively easy to grow, achieving high yields and good-quality heads requires careful attention to every stage of production. In the first part of this series, we look at the fundamentals of cabbage production, including site selection, crop rotation, sowing, spacing and transplanting.

Cabbage (Brassica oleracea) belongs to the Cruciferae family, which includes broccoli, mustard, cauliflower, Brussels sprouts and kale. It is easy to grow cabbage, but pests and diseases need to be controlled throughout the growing cycle.

The foundation for a productive cabbage crop is laid long before the plants begin forming heads. Good soil preparation, proper crop rotation and careful crop-establishment practices help to ensure healthy, vigorous plants.

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Climate

Cabbage is a cool-season crop, but new varieties are extending the seasonal range. When suitable cultivars are used, it can be grown throughout the year in most areas. It is fairly resistant to frost and can survive temperatures as low as -3°C without harm, but thrives in an optimal temperature range of 15-20°C.

Poor environmental conditions during the growing period can lead to quality problems when the cabbages are harvested. High temperatures and low moisture levels may result in small plants and a low yield. Too-low temperatures during the growing period can lead to long stems and bolting (flower stalk formation and seeding).

The soil

Cabbage can be grown in almost any soil type. Well-drained, fertile soil with a high organic matter content contributes to a successful crop. A soil pH of 6,5 to 7 is recommended.

Crop rotation

Rotate cabbages with unrelated crops such as beans, peas, tomatoes, pumpkin, potatoes, sweet potatoes or maize.

Cabbage is a heavy nitrogen feeder. Legumes such as beans and peas will help to replenish soil nitrogen. Maize produces large amounts of organic matter, which will benefit subsequent cabbage crops.

Avoid rotating cabbages with other cruciferous crops, such as broccoli, Chinese cabbage or cauliflower, as they can harbour the same pests and diseases.

Sowing

Sow seed in a nursery and transplant the seedlings about three to four weeks later. Prepare a fine seedbed. Create shallow furrows 15 cm apart and a fingernail deep, and sow seeds 5 cm apart in the row. Cover the seeds with light soil and gently compress the soil with your hand. Put dry grass on top of the bed to stop the soil drying out.

Irrigate the seedbed every day during cooler weather and twice a day if it is hot and dry. Remove the grass four to five days after the seedlings emerge. If the grass is left on for too long, plants become leggy and get sunburn.

The seedlings should be ready for transplanting four to six weeks after sowing.

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Spacing

The planting distance depends on the cabbage variety and the target market. Varieties that have big heads need more space than cultivars with small heads.

Plant small-head varieties 30 cm apart in the row, with 50 cm between rows.

Plant big-head varieties 50 cm apart in the row, with 70 cm between the rows.

Planting times

In South Africa, cabbage can be grown throughout the year, except on the Highveld, where it should preferably not be sown between May and July because of the cold. In the Lowveld and other regions with very hot and humid conditions, cabbage should not be sown during the summer months.

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Transplanting seedlings

Seedlings should be about 10 cm tall before they are transplanted. Irrigate the soil first, and transplant them in the morning or late afternoon, when it is cooler.

Remove the seedlings from the seedbeds or trays with soil or growing medium adhering to the roots. Make planting holes and place the seedlings in them, positioning each one slightly deeper than it grew in the nursery. Firm the soil gently around each seedling, taking care not to pack it too tightly against the stem. Water immediately after transplanting.

Seedlings can be hardened off before transplanting by gradually exposing them to field conditions, thereby reducing transplant shock. Transplant only healthy, good-quality seedlings with well-developed growing points. Discard weak, leggy or unhealthy seedlings.

In Part 2, we will focus on crop nutrition, irrigation, harvesting, crop management and controlling the major pests and diseases that threaten cabbage production.

This article was first published in the Agricultural Research Council’s “Production Guide for Winter Vegetables”.