Chilli peppers

Growing your own chilli peppers means you can choose from a huge array of colours, shapes, flavours and levels of heat – a much wider range than you can buy in supermarkets. Chillies are easy to grow in pots in a greenhouse or, after starting off indoors, can be grown outdoors in a warm sunny spot.

Jobs to do now

  • Harvest fruit as it ripens

Month by month

Sow

Sow seeds indoors from late winter to mid-spring – an early start will give you earlier and longer harvests.

Fill a small pot with seed compost, firm gently then sow a few seeds on top. Most seeds will germinate, so only sow a few more than you need, in case of losses. Cover with a fine layer of vermiculite, pop in a plant label and water.

Seeds will germinate quickly in a heated propagator at 21ºC (70ºF) or simply put the pots on a warm sunny windowsill. Place a clear plastic bag over each pot, secured with an elastic band, to raise the humidity.

As soon as seedlings appear, take the pot out of the propagator or remove the plastic bag. Keep plants at 16–18ºC (60–64ºF) in good light and water regularly.

When the seedlings are 2.5cm (1in) tall, move each one into its own small pot filled with multi-purpose compost. 

If you don’t have time to sow seeds, or don’t have a suitably warm, bright place to raise good plants, then buy young chilli plants from garden centres in late spring. Grafted seedlings can also be ordered from online suppliers for delivery from mid-April. These vigorous plants are especially useful where growing conditions are a little cool.

Grow

While plants are still growing indoors, move them into larger 13cm (5in) pots when roots begin to show through the drainage holes in the base.

When they reach about 20cm (8in) tall, or if they start to lean, stake with a thin cane.

Pinch out the shoot tips when plants are about 30cm (1ft) tall to encourage lots of branches, which should give you more fruit.

By late May, move each plant into its final 22cm (9in) pot or plant three in a standard growing bag. The plants will grow and crop best if kept in a greenhouse, polytunnel, conservatory or coldframe. However, in mild parts of the country you can move them outside, once all danger of frost has passed. 

Chilli plants will tolerate a minimum night temperature of 12ºC (54ºF), but better results are achieved above 15ºC (59ºF), and avoid temperatures over 30ºC (86ºF) as this can reduce fruiting. 

Outdoors, chilli plants can be kept in large containers or planted in the ground in a very warm, sunny, sheltered location. 
 

Planting out

Before planting chillies outside in late May/early June (after the last frost), harden off plants for two to three weeks. Also, warm the soil with polythene or cloches two weeks ahead of planting.

Chillies need your warmest, sunniest spot to produce a good crop outdoors. They also like well-drained, fertile, moisture-retentive soil, which is slightly acid. To achieve this, dig moderate amounts of well-rotted manure (5.4kg/10lb per sq m/yd) into the soil before planting, but avoid using fresh manure or large quantities, as this may lead to lush, leafy growth at the expense of fruit. 

Space plants 38–45cm (15–18in) apart, depending on the variety. Dwarf varieties can be spaced 30cm (1ft) apart. Cover plants with fleece or cloches to provide wind protection, preferably until the end of June.
 

Watering and feeding

Water little and often to keep the soil evenly moist, avoiding waterlogging and drought. Mulch the soil surface to help retain moisture.

Plants in containers need to be monitored regularly to ensure they don’t dry out. 

Maintain a humid atmosphere in greenhouses by damping down twice a day during hot weather.

For a bumper crop, feed plants with a high-potassium liquid fertiliser weekly, once flowering starts.
 

Pruning and supporting

Chillies naturally branch into two or more stems with a flower bud at the joint. To encourage side-shoots on slow-growing plants, pinch out shoot tips once plants reach 30cm (1ft) tall.

Staking may be needed for large plants and those in growing bags. Several canes should be used per plant, as the stems are brittle.

Common problems

Aphids
Aphids

Look for colonies of greenfly on the soft shoot tips of plants or on leaves. They suck sap and excrete sticky honeydew, encouraging the growth of black sooty moulds.

Remedy

Use your finger and thumb to squash aphid colonies or use biological control in the greenhouse.

Whitefly
Whitefly

Small white flies suck sap and excrete sticky ‘honeydew’ over the plant, encouraging the growth of sooty mould.

Remedy

Use biological control or sticky traps in the greenhouse.

Grey mould
Grey mould

A usually grey, fuzzy fungal growth which can begin as pale or discoloured patches. Grey mould ( botrytis) is a common disease especially in damp or humid conditions. Spores enter plants via damaged tissue, wounds or open flowers. Mould can also damage ripening fruit such as strawberries. Black resting spores survive over winter.

Remedy

Remove damaged plant parts before they can become infected. Cut out infected areas into healthy tissue and clear up infected debris. In greenhouses, reduce humidity by ventilating and avoid overcrowding of young plants and seedlings.

Glasshouse red spider or two spotted mite
Glasshouse red spider or two spotted mite

Leaves become mottled, pale and covered in webbing, on which the mites can be clearly seen; leaves also drop prematurely.

Remedy

They thrive in hot, dry conditions, so mist plants regularly. Use biological control in the greenhouse.

Harvesting

Chillies are generally ready for harvesting from mid-summer into autumn if grown in a greenhouse. Fruiting outdoors should start by August.

  • Pick fruits when they are green to encourage further cropping. Left on the plant, fruits will change colour and develop a hotter flavour 

  • If fruit is left to ripen on the plant, new flowers are not formed and this can lead to a reduction in the overall harvest of 25% or more 

  • Because mature fruits are more colourful and better flavoured, the smaller harvest of mature fruit is often thought to be worthwhile

  • At the end of the season, chillies can be harvested and used fresh or made into pickles and sauces 

  • Chillies will eventually shrivel up and dry on the plant or can be picked and dried in an airing cupboard, then used as flakes in cooking

Recipes

Nigel Slater uses chillies in his delicious spiced pork patties in lettuce leaves.

Recommended Varieties

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.