Sweet Peppers

Capsicum annuum is the best-known domesticated species of pepper in the world and contains a huge number of varieties including the sweet peppers we are talking about, but also hot peppers such as jalapenos and cayenne peppers. Sweet peppers are devoid of the chemical ‘capsaicin’, which is present in other peppers and gives them their heat. The sweet pepper, native to the tropics of Central and South America, has probably been cultivated for thousands of years, and archaeologists exploring prehistoric caves in Peru have discovered the remains of pepper seeds. Like many other foods native to this region, sweet peppers were carried throughout the world by the Spanish and Portuguese explorers who travelled through this continent. Because of this they are today an integral part of a variety of cuisines throughout the world.

If you find it easy to grow chillies and wonder why you don’t have the same success with sweet peppers, here’s the answer. Sweet peppers have a weaker root system, which makes them sensitive to a whole host of problems: overwatering, nutrient deficiencies, damping off, viruses that cause deformed fruit, and more. That’s the reason why sweet peppers are generally more expensive than other vegetables, explains Johan Stronkhorst, specialist consultant for capsicums and other fruiting vegetables, for Sakata. In fact, commercial farmers are grafting sweet peppers onto chilli rootstock as an experiment to improve yields and performance. Home gardeners don’t have that luxury, but following some basic do’s and don’ts will improve your chances of success, says Johan.  It really makes sense to grow your own sweet peppers. Ripe peppers are expensive to buy, and well-tended bushes can bear fruit on and o for up to six months. They are also luscious to look at and can even be grown in pots. Peppers contain plenty of vitamins and minerals, although they are not short on calories because of the sweetness. They are delicious eaten raw, or chopped into stir-fries, sauces, casseroles and stews, and can even be pickled.


Sweet peppers are extremely adaptable plants, enjoying both tropical and temperate climates. While peppers are not overly fussy about their growing conditions, they prefer a light, well-draining soil and a warm climate. Peppers grow best in full sun (except those in pots), but can take afternoon shade.

Sweet peppers can be sown until December, directly into the ground or in seed trays (usually the preferred option). Prepare about six stations, each with compost and a handful of 2:3:2 fertiliser. Either sow 4 – 5 seeds per station at a depth of 1.5cm, or plant established seedlings. When planting seeds, thin out the new seedlings to allow the strongest seedling to remain. Each station should be 60 – 80cm apart.

Peppers need regular and thorough watering, especially while the flowers are developing. This will help the fruit to set and mature well. Mulch each plant to keep the soil moist and the weeds at bay. Fertilise plants when flowers start to appear and again after two months to keep the plant fruiting. If necessary, support the stem with a stake once the fruit starts to form and weigh down the plant.

Growing sweet peppers in pots

While sweet peppers can be grown in pots, they suffer from water stress a lot faster than plants in the ground. Here are some tips for pots:
● Grow peppers in a good-size pot, the minimum being a 20-litre pot.
● Use a good-quality potting soil and add vermiculite (25% of the mix) as this retains water, but still allows for good drainage.
● Place pots in semi-shade. Morning sun and afternoon shade is safest.
● Mulch the surface of the pot to keep the soil cool. This also prevents the soil from compacting when watered by hose.
● Water daily in summer.
● Feed more regularly as nutrients leech out with the watering.


The plants will start to set fruit around 60 – 75 days after transplanting, and the larger fruit can usually be harvested about two weeks later. Green peppers are just unripe yellow, red or purple fruit. They can be picked green if you like the flavour or left to ripen fully for a much sweeter flavour. Picking peppers when green will encourage the plant to produce more flowers, and therefore fruit. Sweet pepper plants are brittle and should be handled with care: harvest fruit regularly to prevent the branches from breaking, and cut the stem of the fruit with a pair of secateurs or a sharp knife. Allow the peppers to mature on the plant for the highest levels of vitamin C.

Be careful of overfeeding

When sweet pepper plants are very happy, don’t feel the need to produce. Too much nitrogen will encourage plants to abort the flowers. Reduce watering and stop feeding to encourage the plants to flower.

Don’t overwater:

Peppers need well draining soil and won’t cope with wet feet. The soil should almost dry out between watering.

Look out for:

Wilting leaves can be a sign of overwatering or under-watering, which is why it is so important to check the soil moisture levels. Dig a small hole next to the pepper. If it is bone-dry 30cm down that means that you need to increase watering. But if it is very wet, reduce watering.

Build a strong plant frame:

To get a strong, bushy plant, remove early  flowers on a plant that is less than 40cm high. Once the plant starts to develop fruit it stops growing. By removing flowers, the plants energy is channeled into growing which will lead to a taller plant with more fruit. If the leaves are small, feed with a potassium-rich fertiliser (3:1:5 or 2:3:4). Johan’s rule of thumb is that it takes five good-sized green leaves to produce one fruit. The leaf count will give a good indication of how much fruit to expect and whether to remove flowers.

Practice preventive pest control:

Aphids and thrips are the two main pests for peppers, and both transmit viruses that deforms the fruit and leaves. Thrips also deforms the leaves, which reduces the yield. Indications of a mite infestation include curled leaves, or woody or leathery stems and fruit. Preventing pests before the plants set flowers is very important. To break the lifecycle of the pest, spray every five days for the first two weeks, and thereafter every 7 – 10 days, for six weeks.

Monitor for boron deficiency:

Peppers are sensitive to a deficiency of boron, a micronutrient that is essential for crop health and the uptake of nitrogen and potassium. The symptoms can look like a mosaic virus (curling leaves) or broad mite infestation (cork-like stems and leathery fruit). The best indicator, however, is the appearance of tiny holes in the leaves that look like small hail damage. Best remedy: Buy boracic acid or borax from the pharmacy but use minute amounts, because an overdose will burn the plants. Use ½ml in 5 litres of water and use as a soil drench.

The Gardener