A popular easy to grow vegetable that sells well on most African markets, cabbage has long been touted, by commercial farmers, as the cash crop to grow when things are tight. There never seems to be a shortage of buyers.
Cabbage growers must take care to control pests and diseases during the growing cycle or they can lose the crop. The cabbage belongs to the same family in the plant kingdom as broccoli, mustard, cauliflower, Brussels sprouts and kale (Cruciferae).
Excellent management can yield 60 tons to 80 tons of cabbage a hectare. Can you do it?
The optimum temperature for cabbage is between 15°C and 20°C so cabbage is generally a cool season crop. But, if you plant the right cultivars it’s possible to grow this crop year round in most areas. Although it would not be sensible to grow cabbages in the hottest months of the year in the tropics.
High temperatures and low moisture levels can mean smaller plants and a lower yield, and planting when it’s hotter exposes the crop to more pests. Pests and diseases always thrive in hot, wet conditions.
Cabbage thrives in well-drained fertile soil with lots of organic matter and a soil pH of 6,5 to 7. However, it will tolerate a wide range of soil types.
Contact the seed companies to help you choose the cultivar that suits your area. Cultivars like Hercules and Tenacity do well in summer and spring; while Conquistador and Gladiator prefer autumn and spring. (See below for suppliers)
Rotate cabbages with unrelated crops like tomatoes, pumpkin, sweet potatoes, beans, potatoes or maize.
Cabbage is a heavy nitrogen feeder so it’s a good idea to rotate with a legume crop like beans, which fixes nitrogen, and grain crops which leave behind organic matter to improve the soil.
Don’t rotate with other cruciferous crops (Chinese cabbage, cauliflower) because they can harbour the same pests and diseases that will attack your cabbage crop.
THE NURSERY – SOWING
Sow the seed in a nursery and transplant it three to four weeks later, when the plant is about 10cm high.
Prepare a fine seedbed and make shallow drills (furrows) 15cm apart and a fingernail deep. Sow the seed 5cm apart in the row.
Cover with light soil and gently compress with your hand.
Put dry grass on top of the bed to stop the soil from drying out.
Irrigate your cabbage every day when it’s cooler and twice a day when temperatures go up during the hot dry season.
Take the grass off four to five days after the seedlings emerge. If you leave it on for too long the young cabbage plants get sunburnt and leggy.
Seedlings should be ready for transplanting four to six weeks later.
THE FIELD – PLANT SPACING
The planting interval depends on the cabbage variety and the target market. Cabbages with big heads need more space than those with small heads. Small head varieties need to be 30cm apart in the row and 50cm between rows; these varieties are good for fresh produce markets. Big head varieties should be 50cm apart in the row with 70cm between rows; these varieties are good for hawkers’ markets.
THE FIELD – TRANSPLANTING
Irrigate the land before you transplant the 10cm high seedlingS, and transplant in the morning, or in the late afternoon, when it is cooler. Take the seedlings out of the trays or seedbeds and leave some of the growth medium on the roots when you transplant.
Place the seedlings into shallow holes you have made in the soil, and water immediately. Only transplant healthy, good quality seedlings and discard anything you think looks unhealthy, or is long-legged and weak.
Cabbage is a heavy feeder that does very well when fed with manure and compost and organic fertilisers. But remember – the fertiliser application rate can only be worked out once the correct soil analysis has been made.
Especially at start-up it really is important to have a soil analysis done. After that it’s a good idea to analyse the soil once a year, but twice a year will also do.
Dig in 2:3:4 (27) (nitrogen: phosphorus: potassium) at 60g to 90g per m²; this is the minimum amount of fertiliser needed to give the plants a good start. The optimum (best) fertiliser rate is 1 200kg of 2:3:4 per ha.
Cabbage plants respond well to a top dressing, spread about 20cm around the plant, of LAN 28% nitrogen at two, four and six weeks after transplanting. Start with 4g per plant and increase it to 10g per plant.
Don’t fertilise after the cabbage head has formed because it can cause splitting and more leaf development. You will get poor, loose heads; not a winner at the market.
Cabbages must have sufficient water immediately after sowing or transplanting. The young plants need enough water to grow decent leaves before the head forms. The bigger the plant is at this stage the larger the eventual cabbage head will be.
The optimal water application is 30mm a week. Too much water after head formation will cause cracking, which you do not want.
Inconsistent watering, giving the crop a lot of water in the beginning and then tapering off later, can also lead to cracking.
Start weeding when the young plants are established and carry on until the cabbage leaves cover the ground. Be careful not to damage the plant roots when weeding. Irrigate throughout the growing period and conserve water by mulching.
Always harvest your cabbages in the morning when it is cool and use a sharp knife to cut the heads off. The harvest comes 90 to 110 days after transplanting. Cut so that there are two or three layers of leaf around the head to protect the cabbage during transportation. You can carry on harvesting selectively over several weeks.
Never leave the cabbage heads out in the sun – they will wilt. Store them in a cool shaded place.
Immediately after harvesting, incorporate the crop residues into the soil. You don’t want them lurking around providing suitable homes for next season’s pests.
PESTS AND DISEASES
The pests and diseases that attack cabbages can cause serious damage to the crop and therefore to the farmer’s bottom-line.
Integrated pest management strategies, including scouting (walking the field daily, looking for pests) crop rotation, good crop management, chemical and mechanical control of pests and diseases can be used.
Use registered chemicals only if you need to spray.
For more information visit www.arc.agric.co.za
8th St, Lusaka, Zambia. Phone +260 21 1846367; 260 211 840 965/949
Phone: +263 4 882485/851962
Phone: +265 712074/62
Phone: +267 3911907
Sakata agent – Radseed
” The Spinney” Leopards Hill Road , Lusaka, Zambia
Tel: +260 973 079 611
Klein Karoo Seed
Phone +260 211 840 965/949
Klein Karoo Seed
Phone: +263 4 746179
Phone: +260 21 124 3441