January and February are when the chilli season begins. The seeds need warmth and time, and the seedlings need several months before they are ready for the balcony. Sow early and you will be picking fruit by midsummer.
We filmed a short video that shows the germination stages, from seed to first leaves. Below, the method is set out in more detail, with the temperatures and timings that matter most with chillies.
You can buy chilli plants at a garden centre, but the choice of varieties is small. From seed you can grow almost anything, from mild salad chillies to fiercely hot habaneros.
To grow chillies from seed, sow between January and March, and no later than the end of April. Sow seeds 0.5 cm deep in moist seed compost and keep them at 22–28 °C; they germinate in 7 to 21 days, very hot varieties sometimes later. Pot on each seedling once it has four to six true leaves, and move plants outdoors only after the last frost, usually late May.
When should you sow chillies?
January and February are ideal. Chillies grow slowly and need four to six months from sowing to the first ripe fruit, and very hot Capsicum chinense varieties such as habanero and Carolina Reaper need longer still. Early sowing gives the fruit time to ripen before the end of summer.
You can still sow up to the end of April for a crop, but the fruit will ripen later. For late sowings, choose milder, faster varieties such as jalapeño or cayenne.
What temperature do chilli seeds need to germinate?
Chilli seeds germinate at 22 to 28 °C. Below 20 °C germination slows sharply or stops, so a cold winter windowsill will not do. A heated propagator is the most reliable option. Many British growers also use the airing cupboard, but the tray must come out into the light as soon as the first shoots appear.
At that temperature most varieties germinate in 7 to 21 days. Very hot varieties often take three to four weeks, so do not give up on a tray too soon. Seeds do not need light to germinate, but the moment they break the surface they need plenty of it.
| Stage | Temperature | Duration |
|---|---|---|
| Germination | 22–28 °C | 7–21 days, hot varieties up to 4 weeks |
| Seedlings to first true leaves | 20–24 °C by day, slightly cooler at night | 2–4 weeks |
| Young plants in pots | 18–24 °C | 6–10 weeks |
| Outdoors | nights above 10 °C | from late May until the first frost |
How do you sow chillies from seed in 7 steps?
- Soak. You can soak the seeds in lukewarm water for 8 to 12 hours before sowing. It is not essential, but it speeds germination a little.
- Sow. Fill a seed tray or modules with light, low-nutrient seed compost. Place two or three seeds in each cell, 0.5 cm deep.
- Keep warm and moist. Mist the compost, cover the tray with a lid or cling film and keep it at 22–28 °C. Lift the cover for a few minutes each day so mould does not build up.
- Give light. When the shoots appear, remove the cover and move the tray to your brightest window, ideally south-facing. In winter a LED grow light switched on for 12 to 16 hours a day makes a real difference.
- Thin out. Once the seedlings have a few leaves, snip off the weaker ones at soil level and keep the strongest in each cell. Do not pull them out, or you will disturb the roots of the one you keep.
- Pot on. When the seedlings have four to six true leaves and are about 5 cm tall, move each into its own 9–10 cm pot. Left too long in the tray, the roots run out of room and growth stalls.
- Harden off and plant out. When plants reach 10 to 15 cm and nights stay above 10 °C, put them outside for a few hours a day over one to two weeks. In most of the UK that means late May, in the north often early June. Then plant them into final pots holding 10 to 15 litres of compost, or into a greenhouse bed.
Why are my chilli seedlings tall and thin?
Leggy seedlings leaning towards the window are short of light. Too much heat after germination is another common cause: on a heat mat they grow fast but weak. Once they are up, take them off the heat and keep them somewhere bright at 20 to 24 °C.
Gentle air movement strengthens the stems. A small fan helps, or simply brush your palm lightly over the tops of the seedlings once a day.
How do you pot on chillies without damaging the roots?
Chillies dislike root disturbance. Grow one plant per final pot, and pot on only when the roots fill the compost of the smaller pot, not before.
Water the seedlings just before moving them, so the compost holds together around the roots. Turn the pot over, hold the seedling by a leaf rather than the stem and ease it out. Set it in the prepared hole, fill around it with compost, firm gently and water in.
Can you grow chillies on a balcony or in a vertical garden?
Yes. Chillies are among the most rewarding balcony plants if they get at least six hours of sun a day and shelter from wind. South- and west-facing balconies suit them best. For smaller pots, choose compact or ornamental varieties that grow to 40 or 50 cm.
If you would rather not fill the balcony with pots, grow upwards. With a vertical garden without drilling, a telescopic pole clamps between floor and ceiling, adjusts up to 285 cm and holds nine pots on less than 1 m² of floor. Put compact chillies in the top pots, where the sun is strongest. Each pot has a 300 ml water reservoir, so watering once or twice a week is usually enough, though in hot spells check the compost more often. The Urban Planty Vertical Garden costs €149 with free shipping.
Basil or parsley make good neighbours in the pots below. The most common mistakes with herbs are covered in our balcony herb garden guide. If all you have is a north-facing window, chillies will not fruit there; low light houseplants are a better choice for that spot.
Can you overwinter chilli plants?
Chillies are perennials that we usually grow as annuals. In autumn, before the first frost, cut the plant back by about two thirds, bring it into a bright, cool room at 10 to 15 °C and water sparingly. In spring it starts growing earlier than seed-sown plants and fruits sooner.
Once the seedlings are up, our guide on how to grow chillies in pots covers feeding, pollination and overwintering.
Frequently asked questions
How long do chilli seeds take to germinate?
At 22 to 28 °C, most varieties germinate in 7 to 21 days. Very hot varieties such as habanero often take three to four weeks.
Why are my chilli seeds not germinating?
The usual cause is too little warmth: below 20 °C germination almost stops. Other causes are waterlogged compost, sowing too deep and old seed, which loses viability after a few years.
Do chilli seeds need light to germinate?
No, they need warmth and moisture. As soon as the shoots break the surface, though, they need plenty of light or they will become leggy.
When can chilli plants go outside in the UK?
When nights stay above 10 °C, which in most of the UK is late May or early June. Harden them off for one to two weeks first by putting them outside for a few hours each day.
What size pot does a chilli plant need?
Larger varieties need a final pot holding 10 to 15 litres of compost. Compact ornamental varieties manage in a smaller pot, but it needs watering more often in summer.
