Chillies are frost sensitive perennials that are treated as annuals in the UK.

They require relative warmth and good light.

They can grow to a height of 900mm (36") depending upon variety.

This characteristic will often determine if the plants are to be grown in pots or in the greenhouse border.

If grown in the greenhouse border they should be planted out 500-600mm (18"-24") apart.

Smaller varieties can be grown in containers suited in size to the eventual height and spread of the variety.

The white flowers appear from June to August.

The fruits come in a range of size, colour and shapes, e.g. 12mm-200mm (½"-8") long, red, yellow or green in colour, and spherical, conical or twisted in shape.

Subject to your geographical position in the UK i.e. in warm sheltered areas in the south and west, they may be grown outdoors, and in cooler northern areas they can be stood outside in pots during the summer and brought indoors when the weather becomes cooler.

Week 10; Sow seeds in pots of seed compost at a temperature of 21 °C (70°F) as shown here;

Germination should take around 7-14 days

Week 14; When the seedlings are large enough to handle, prick them out individually into 75mm (3") pots of potting compost and pot on as necessary.

Start feeding with a balanced or high-nitrogen fertiliser until the plants are about 12.5cm (5in) high.

Week 20; If the intention is to grow the plants outdoors, harden off plants in a cold frame before planting out. 

Week 22; Plant out in a well-drained, fertile and moisture-retentive greenhouse border,500-600mm (18"-24") apart, 300-400mm (12”-16") for dwarf cultivars.

Alternatively; pot up into 150-250mm (6"-10") pots depending upon variety.

Note; Tall growing cultivars and those with large fruit will require some means of support to hold them upright, the weight of fruit can make their branches break.

Week 23; Plant out doors after the danger of frost has passed.

Generally;

Maintain a minimum night temperature of 12°C (54°F), but better results are achieved above 15°C (59°F).

Avoid temperatures above 30°C (86°F) under glass, by providing maximum ventilation, and lightly shade the glass during the hottest months

Maintain high humidity in glasshouses by damping down twice a day in hot weather.

Water regularly but do not overwater, and give a balanced liquid fertiliser every 7-10 days.

Ensure water and feed are at air temperature! chillies react badly to cold compost.

Water little and often to keep soil evenly moist, avoiding both water-logging and drought

Closer attention to watering and feeding is necessary with chillies in containers; ensure they never go short of water and are adequately fed, a weekly bal­anced liquid feed is ideal.

Spray the leaves daily with water during the flowering period to assist fruit setting.

Pinch out growing tips* when plants reach 300mm (12”) tall to induce more fruiting branches.

* This task is optional; i.e. with some of the taller varieties this may not be required due the amount of fruit they produce naturally.

Note; encouraging plants to produce more fruit may give you the desired quantity at the expense of quality.

The reverse is generally true for low growing varieties

Give a high-potassium liquid fertiliser at 7-10 day intervals after the fruits first appear and until they show a change in colour.

With indoor plants, insect pollination can sometimes be insufficient, to ensure good fruit set pollinate manually with a small artists paintbrush.

The fruits should be ready for picking in September / October depending upon variety.

Potential problems;

Chillies are relatively trouble free and are threatened by only a few pests and diseases, e.g.

Botrytis (grey mould) can appear in late autumn, but by then most of the fruit may well have been harvested.

Red spider mites, whiteflies and thrips sometimes attack chillies, but aphids are the most likely pest to be encountered at home.

Fortunately, these are easy to keep in check: light infestations can simply be rubbed off the plants, while sprays and predators efficiently deal with heavier invasions.

Aphids can transmit tobacco mosaic virus, which causes mottling of the leaves and debilitates plants.

Infected plants should be removed and destroyed.

Growing conditions and cultivation techniques can also affect the yield and quality of chillies.

High-temperature stress, for example, or lack of water, can cause flowers and young fruit to drop, while blossom end rot, a physiological disorder caused by calcium deficiency in the fruit can be caused by low pH, root damage and uneven watering.