Swiss chard can easily be confused with spinach. This is because these green, leafy vegetables only differ slightly in appearance: Swiss chard has bigger, broader leaves and thicker stems. When it comes to nutritional value, both are jampacked with minerals and vitamins, and the only real difference is that spinach is higher in calcium, whereas Swiss chard is higher in vitamin A.
You might also be surprised to know that the plant is actually related to beet, not spinach.
Interestingly, the vegetable did not originate in Switzerland, but rather Italy. It was named, however, after the Swiss scientists who were responsible for classifying the plant.
As a crop, this vegetable delivers an average yield of around 8 to 15 t/ha. The crop is easy to grow and harvest, making it ideal for even the most novice grower to cultivate.
Climatic and soil requirements
Swiss chard is a cool weather crop, but it is not unheard of to also grow it in hot summer months. The optimal temperatures for this crop ranges between 16 °C and 24 °C.
The best times to plant this crop is from August to April, but in warmer areas, it can be planted from March to June.
It fares best in well-drained, loam soil, but it will also grow in clay soil if it is fertile. The acidity of the soil needs to be between 6 and 6,8 pH.
The stem and the leaves are edible, but due to the bitter taste of the stems, the vegetable is usually cooked. Swiss chard’s unpleasant taste is due to the oxalic acid. Cooking the plant destroys these molecules, making the vegetable more palatable.
Start to prepare the soil by clearing the planting area of weeds and grasses. You can do this approximately a month before you plan to plant the seeds.
Water the field and continue to loosen the soil with a fork to prevent the spread of pests and diseases. This helps promote drainage, root penetration and aeration.
Add the fertiliser, manure, or compost.
Loosen the soil with a plough or fork.
Swiss chard requires a lot of compost or manure, in addition to fertiliser. Mix it as instructed and make sure the seedbed is fine. Any big clods can prevent germination.
Swiss chard seeds are directly sowed into the furrows.
Make furrows of 3 cm deep with a spade or rake. Space the rows 25 to 35 cm apart. Sow the seeds 2 cm apart and cover with soil.
Irrigate the seedbed after sowing and cover it with a layer of mulch to keep the moisture from evaporating.
After five to six days, the mulch can be removed to stop seedlings from being too leggy. The seeds should germinate by day eight.
Plants will germinate in seven to eight days. Remove the grass mulch after five to six days to avoid long, leggy seedlings. You can also thin the plants out three weeks after seedlings have emerged, ensuring plants are 10 cm apart.
These plants are top heavy and can easily be damaged by the sun. It is important to thin seedlings out to 10 cm apart, not later than three weeks after the seedlings have emerged.
Before planting, apply 2:3:2 (22) Zn fertiliser. The measure to apply is 900 kg/ha or 90 g/m2. Mix it into the top 10 cm of the soil.
Three weeks after emergence, topdressing can be applied between 5 to 15 cm away from the plants. The quantity to use is 8 g KAN/LAN per 1 m row on each side. Nitrogen is vital for Swiss chard. It ensures the plant produces large, broad leaves.
After another 5 weeks, the same topdressing can be applied again. This time, it can be worked into the top 2 cm of the soil by using a fork. Take care not to damage young, fragile roots.
Irrigate after fertilisation.
Swiss chard has a very shallow root system; therefore it requires regular irrigation – once or twice a week to keep the soil moist.
To stimulate regrowth, and thus obtain a higher yield, plants need to be harvested often. This can be done by cutting off the outer leaves with a sharp knife. Cut the leaves 30 to 50mm above the soil. Do not damage the new shoots.
To ensure freshness, leaves can be bunched and stored in water – almost like flowers – until they are used. You can only refrigerate Swiss chard for up to eight days before it spoils due to its high transpiration rate.
Pest and disease control
Aphids are small insects that suck the fluids from plants and transmit viral diseases. Check your plants regularly to see if there are pests. If you find aphids on your vegetables, you can dilute a teaspoon of dish soap in a litre of water and spray the solution over the plants. Alternatively, you can use registered pesticides such as Phosdrin or Mevinphos.
These pests hide underground during the day and feast on the seedlings at night. You will need to check regularly if your seedlings disappear, but you can use cutworm bait preventatively.
Red spider mite
An early sign of infestation is stippled areas on leaves. Leaves become chlorotic and in severe cases, webs are produced on leaves and stems.
Control: Regular checking is important. Spray with dish soap diluted in water.
Larger insects, which make large holes in the leaves, can cause a lot of damage.
Spray chemicals registered for aphids.
Can be seen as swellings on the roots. Practice intercropping with marigold, mustard, and rapeseed; fallowing. Also use soil solarisation or spray registered pesticides such as Nemacur and EDB.
Swiss chard diseases:
A couple of diseases affect Swiss chard. First, there is cercospora leaf spot, which causes small, dark brown spots on the leaves. The spots have a lighter colour in the centre. Second, there is pythium root rot. It is caused by soil that didn’t drain well after irrigation or rain.
Although there isn’t a registered chemical to control these diseases, there are preventative measures you can follow. These are:
- Rotate crops
- Destroy infected plants by burning them
- Sanitise the field after harvests
- Fertilise plants well
- Don’t over-water
- Water Swiss chard in the morning so the leaves are dry at night
The information provided in this article is credited to the Agricultural Research Council (ARC) ÚRC Vegetable and Ornamental Plant Institute (ARCVOPI). For more information, contact +27(0)12-841-9611 or visit http://www.arc.agric.za.