How to grow chilli peppers

Chilli seeds are widely available in garden centres and from online seed suppliers. There are also many specialist chilli seed retailers, who offer the widest choice of varieties.

Many of these sources also sell young plants in spring and early summer. These are ideal if you don’t have time to sow seeds or don’t have a suitably warm, bright place to raise good plants.

Another option is to buy grafted seedlings, which can be ordered from online suppliers for delivery from mid-April. These more vigorous plants should produce larger crops and are especially useful where growing conditions are a little cool. 

When the seedlings are 2.5cm (1in) tall, move each one into its own small pot of multi-purpose compost. Then, once roots begin to show through the drainage holes, move them into larger 13cm (5in) pots.

By late May, move each plant into its final 22cm (9in) pot or plant three in a standard growing bag. Add canes to keep them stable and upright.

The plants will grow and crop best if kept in a greenhouse, polytunnel, conservatory or cold frame. However, in mild parts of the country you can move them outside, once all danger of frost has passed (see Planting out, below). 

Keep chilli plants indoors until the night temperature is reliably at least 12°C (54°F), usually by late May or early June. Then harden off for two to three weeks, to acclimatise them to outdoor conditions.

Chillies need your warmest, sunniest spot to produce a crop outdoors. They grow well in large containers, ideally on a sunny patio or by a south-facing wall.

They can also be planted in the ground, into well-drained, fertile, moisture-retentive soil that is slightly acid. To achieve this, dig in moderate amounts of well-rotted manure – at a rate of 5.4kg (10lb) per square metre/yard – but avoid using fresh manure or large quantities, as this can lead to lush, leafy growth at the expense of fruit. Then warm the soil with polythene sheeting or cloches for a couple of weeks before planting.

Plant the young chillies in the ground at the same level they were growing in their pot. Space them 38–45cm (15–18in) apart, depending on the variety. Dwarf varieties can be spaced 30cm (1ft) apart. Then cover with fleece or cloches to provide wind protection, preferably until the end of June.

Chilli plants will tolerate a minimum night temperature of 12°C (54°F), but will grow better if kept above 15°C (59°F). However, temperatures over 30°C (86°F) can reduce fruiting, so keep greenhouses well ventilated and put up shading in hot weather.

Chillies like a humid atmosphere, so in hot weather ‘damp down’ the greenhouse twice a day by pouring a full watering can over the floor, then leave it to evaporate.

Water little and often to keep the soil or compost evenly moist, avoiding waterlogging and drought. Add mulch to help hold in moisture. Plants in containers can dry out very quickly, so check them regularly. Flower buds may fall off if plants get too dry.

Feed chilli plants with a high potassium liquid fertiliser weekly, as soon as flowering starts.