Peppers and chillies

Sweet peppers and chillies can be grown in pots on a sunny, warm patio in a similar way to tomatoes, but will produce a better crop when grown in a greenhouse or conservatory. Chillies and peppers are green when young, maturing to a variety of colours and flavour varying from mild to extremely hot.

Peppers and chillies

Quick facts

Common name Sweet peppers and chillies
Botanical name Capsicum annuum
Group Vegetable
Flowering time Summer
Planting time Spring to early summer
Height and spread Various 
Aspect Sun
Hardiness Tender
Difficulty Moderate


Peppers and chillies need a warm, sunny sheltered position and, therefore, are only suitable for outdoor cultivation in milder parts of the country, and benefit greatly from cloche or even fleece protection. They can be grown in frames, unheated polythene tunnels or greenhouses and are also suitable for growing in containers or grow bags filled with multipurpose compost.

They require well-drained and fertile, moisture-retentive soil, which is slightly acid. To achieve this, incorporate moderate amounts of well-rotted manure (5.4kg per sq m/10lb per sq yd) into the soil, but avoid using fresh manure or large quantities, as this may lead to lush, leafy growth at the expense of fruit.

Growing peppers and chillies

Plants will be ready for planting in their permanent position or for potting-on when they have reached flowering size, approximately eight weeks after sowing.

  • Space plants 38-45cm (15-18in) apart, although dwarf cultivars can be spaced 30cm (1ft) apart, if planted in the ground
  • Alternatively, plant two to three plants per growing bag or one plant per 22.5-25cm (9-10in) pot
  • Water little and often to keep the soil evenly moist, avoiding waterlogging and drought. Growing bags need to be monitored regularly to ensure they don’t dry out. Mulch soil-grown plants to help retain moisture
  • Feed plants with a high-potassium liquid fertilizer weekly, once the first fruit has set
  • Plants will tolerate a minimum night temperature of 12ºC (54ºF), but better results are achieved above 15ºC (59ºF), and avoid temperatures above 30ºC (86ºF) as this can reduce yields
  • Maintain a humid atmosphere in greenhouses by damping down twice a day in hot weather


  • Pick fruits when they are green to encourage further cropping. Left on the plant, fruits will change colour and develop a sweeter (peppers) or hotter (chillies) flavour
  • If fruit is left to ripen on the plant, new flowers are not formed and this can lead to a reduction in yield by 25% or more
  • Because the mature fruits are more colourful and better flavoured, the lower yield of mature fruit is often thought to be worthwhile
  • The first fruits should be ready for picking under cover from July or outdoors from August
  • At the end of the season, peppers and 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 and used as flakes in cooking

Pruning and training

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

Staking is needed for high yielding plants and those grown in growing bags. Several canes should be used per plant as the stems are brittle.


In mid-February or early March, sow fresh seed for plants that are to be grown under glass, and in late March or early April for peppers to grow outdoors.

  • Fill trays, pots or modules with multipurpose compost
  • Level and firm the compost, then water
  • Sow seed and cover to a depth of 6mm (¼in) with vermiculite
  • Maintain at 21ºC (70ºF) until seedlings germinate, ideally in a heated propagator
  • Transfer seedlings to a heated greenhouse at 16-18ºC (60-64ºF) with good light

If you can’t provide sufficient heat and light for germination and growing on, young plants can be purchased from garden centres in spring. Grafted seedlings of both chillies and peppers can also be ordered from suppliers for delivery from mid-April and are especially useful where growing conditions are a little cool.

Growing on

Once seedlings are 5cm (2in) high, transplant them into 9cm (3½in) pots, maintaining high temperatures to encourage growth. They can then be potted on into 10-12.5cm (4-5in) pots, once their roots fill the compost.

Growing outdoors

Harden off plants for two to three weeks, before planting outside in late May/early June, once all danger of frost has past. Warm outdoor soil with polythene or cloches two weeks before planting out. Cover plants with a layer of fleece to provide wind protection, preferably till end of June.

Cultivar selection

Sweet peppers

‘Ariane’ F1 AGM: Early-cropping, bell-shaped fruits ripening to orange.
‘Artis’ F1 AGM: Fruits are horn shape and fleshy, ripening to deep red. Produces a heavy crop.
‘Friggitello’ AGM: A productive plant with small, pointed, red fruits which are suitable in stir-fry and pickling.
‘Gypsy’ F1 AGM: An old favourite with a high yield of long, blocky, bright-red fruit.
‘Redskin’ F1 AGM: High yield of small to medium blocky, glossy-red fruit, borne on compact plants which are suitable for growing in pots.


‘Apache’ AGM: Does well in pots and produces a large crop of small, juicy, hot peppers.
‘Caribbean Antillais’ AGM: Small, blocky, aromatic, red fruits that are very hot and suitable for South American and Caribbean cooking. Best sown in January with higher temperatures to improve germination.
‘Demon Red’ AGM: An abundant crop of upward pointing, bright-red fruit that are hot and used in Thai cooking.
‘Fiesta’ AGM: A highly ornamental plant covered in jewel-like, small, conical fruits that ripen through purple, yellow, orange to bright red. A spice type and the fruits are hot to very hot.
‘Habanero’ AGM: Very hot, blocky, orange fruit borne on compact plants suitable for growing in pots. Best sown in January as a later-cropping cultivar.


Peppers and chillies are commonly attached by aphids, red spider mites and whitefly in cold frames and greenhouses but biological control can be effective.

Botrytis (grey mould) can occur on stems, petioles and fruits in cool, wet weather, but quick removal of diseased material and increasing air circulation reduces damage. Soil-borne disease such as verticillium wilt and sclerotinia can be an issue, so grow on a fresh site or in growing bags.

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