Growing chillies indoors on a sunny windowsill

Chillies are made for windowsills. They’re compact, they like warmth, and they crop for months indoors. Sow in late winter, about 6 to 12 weeks before your last spring frost, and grow them on the sunniest window you have.

The two things indoor plants miss out on are light and pollinating insects. Give them more of the first, and help with the second, and a single plant can give dozens of chillies.

Choosing a variety

Look for compact varieties sold for pots or windowsills. Apache is a well-known compact, medium-hot chilli that stays around 45 cm tall indoors. Many ornamental chillies are also edible and very hot, though check the label.

Very large or very hot varieties, such as habaneros, grow indoors too but need a longer season and more light.

Sowing

Chilli seed needs warmth to germinate, ideally around 25 °C.

1. Sow two or three seeds about 0.5 cm deep in a small pot of seed compost.
2. Cover with a clear bag and keep it somewhere warm, such as a heated propagator or a warm shelf.
3. The seedlings appear in one to three weeks. Move them into bright light at once.
4. Thin to the strongest seedling, or move the spares into their own pots.

Indoors you’re not tied to frost dates, but a late-winter sowing lines up the main growth with the long, bright days of summer.

Pots and light

Pot the plant on as its roots fill each pot, ending in a 2 to 5 litre pot with drainage holes. Bigger pots give bigger plants.

Put it on your sunniest windowsill, ideally facing south. Turn the pot every few days so it grows evenly. If the plant stretches and leans, it needs more light. A small LED grow light is a good investment for late winter and autumn.

Watering and feeding

Water when the top of the compost is dry to the touch, and let any excess drain away. Chillies dislike sitting in wet compost, especially in cool rooms.

Once flowers appear, feed every week or two with a high-potash liquid feed such as tomato food.

Pollinating by hand

Outdoors, wind and insects move pollen between flowers. Indoors, gently flick each open flower, or dab the centre of each one with a soft paintbrush or cotton bud, moving from flower to flower, every couple of days while the plant is in flower. Without this, many flowers drop without setting fruit.

Picking

Chillies are ready about 70 to 100 days after the plant goes into its final pot, usually from midsummer. Pick them green for a fresher, milder flavour, or leave them to ripen to red, orange or yellow for more heat and sweetness. Picking regularly encourages more flowers.

Keeping plants over winter

In autumn, once fruiting slows, cut the plant back by about half. Keep it somewhere cool and bright, around 10 to 15 °C, and water just enough to stop the compost drying out completely. In late winter, repot it in fresh compost, move it somewhere warmer and resume feeding. Overwintered plants flower and fruit weeks earlier than new ones.

Common problems

Aphids. Common indoors, clustering on shoot tips and under leaves. Squash them, or wipe them off with soapy water.

Flowers dropping. Usually no pollination, dry compost or very hot, dry air. Pollinate by hand and water regularly.

Leggy, pale plants. Too little light. Move them closer to the window or add a grow light.

For chillies in a greenhouse or garden, see when to sow chillies in the UK, and set your own frost dates on the chilli page.