This dark green, leafy vegetable has high yields if it is regularly harvested. The growing season can be lengthened to between 5 and 7 months as long as there are no adverse weather events.
Swiss chard looks a lot like spinach but has broader leaves and thicker stems, both of which may be eaten. This annual vegetable with its high yields and attractive marketing qualities make it a winner for fresh produce growers.
SOIL AND TEMPERATURES
Swiss chard needs fertile, well-drained soil. Sandy loams are best but it will do well in loamy to clay soil with a pH of 6 to 6.8. Correct acid soil pH with lime and organic matter.
Although this is a cool weather crop with optimal temperatures ranging between 16˚C and 24˚C, Swiss chard can tolerate higher temperatures.
CHOOSE THE CULTIVAR
Swiss chard is a heavy feeder that needs a good water supply.
When you select seed, or buy seedlings, think about your requirements. You may need a cultivar that tolerates higher temperatures, or one with faster growth and higher yields but less resilience in hotter months. There is also the rhubarb cultivar with reddish coloured leaves and good yields. Base your choice on local environmental conditions and on market preferences.
CROP ROTATION AND LAND PREPARATION
Rotate Swiss chard with other vegetables like pumpkins, beans, peas, tomatoes, potatoes and cabbage. Failure to rotate leads to a build-up of pests and diseases.
Conventional methods advise clearing the plot of weeds a month ahead of planting and loosening the soil with a fork to prevent pests and diseases from infecting the new crop.
A good watering will prevent compaction and enhance root penetration and aeration. Loosen again with a plough or fork.
Swiss chard needs a lot of compost or manure as well as fertiliser.
The seed bed must be well prepared for direct sowing and have a fine structure. Big clods of earth will prevent germination.
Seeds can be sown 2 cm apart into shallow, raked rows 2 cm to 3 cm deep and then covered with soil.
Plant seedlings 10 cm to 20 cm apart in rows 25 cm to 30 cm apart.
Immediately after sowing, water the soil and cover with a thin layer of mulch, especially in hotter months. Remove the mulch after five or six days to avoid leggy seedlings.
Top dress three weeks after transplanting or emergence at a rate of 16 g of LAN per 1 m row. Apply the fertiliser 5 cm to 15 cm away from the plant on both sides. This means that 8 g of LAN is applied down one side of the 1 m row and 8 g down the other side of the same row.
This top dressing is vital because Swiss chard needs a lot of nitrogen to produce good quality, broad leaves and therefore good yields.
Apply a second top-dressing 8 weeks after emergence of transplanting, especially in sandier, lighter soils. Never apply the LAN directly onto the plants. It will burn them.
Growers can apply fertiliser by hand, which is time consuming and back breaking or they can look at buying a hand-held fertiliser applicator.
Michris Janse van Rensburg, a farmer and implement designer, has manufactured a fertiliser applicator that can be calibrated to deliver the right amount of fertiliser. It’s a huge labour-saver for small-scale commercial farmers and has the potential to increase the area under cultivation.
Water the plants immediately after fertilising.
Swiss chard has a shallow rooting system and soil must be kept moist throughout the growing season. This crop needs irrigation at least once, but possibly twice, a week.
Harvest regularly to stimulate a higher yield, removing only the outer leaves with a sharp knife 30 mm to 50 mm above the soil. Take care not to damage new shoots.
If the leaves are not used immediately they can be tied into bunches and placed in water to keep them fresh. But they cannot be kept like this for too long before the leaves begin to wilt.
In a cold store or a fridge leaves can be stored for about five days. Ideally, you want to market Swiss chard a day or 2 after harvesting.
- Resource: Agricultural Research Council of South Africa; Vegetable and Ornamental Plant Institute.
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