Chillies and peppers are the crop that taught me patience. The first year I grew them I sowed the seed in April, like I did with everything else, and ended up in October with healthy green plants covered in fruit that never ripened before the cold killed them. It took me a season or two to understand the one thing that matters most with these plants: in the UK, you have to start them ridiculously early, because they need every single day of warmth our short summer can give them. Get that right and they are genuinely rewarding. Get it wrong and you grow lovely leafy plants and no usable crop.
Peppers and chillies are the same plant family and grow in almost exactly the same way, which is why I am covering them together. Sweet peppers (bell peppers) and hot chillies differ only in heat and, slightly, in how long they take to ripen. Everything about sowing, growing, feeding and ripening applies to both. After twenty years of growing them in Oxfordshire, in a greenhouse, on windowsills, and outdoors in good summers, this is what actually works in the UK climate.
The Golden Rule: Sow Early
If you take one thing from this whole guide, take this: chillies and peppers must be sown early, far earlier than almost anything else you grow. The reason is simple. They originate from hot climates with long growing seasons, and they need a long warm period from sowing to ripe fruit, often five to six months for chillies and even longer for the hottest superhot varieties. Our UK summer is nowhere near long enough if you start late.
Sow chilli and pepper seed indoors between late January and early March. The hotter the variety, the earlier you sow, because superhots like habanero, scotch bonnet and carolina reaper take the longest to ripen. Sweet peppers and milder chillies can go in slightly later, into March, but earlier is nearly always better. By the time the conventional sowing season arrives in April and May, it is honestly too late for a reliable crop of ripe chillies outdoors in most of the UK.
This is the single most common reason people fail with chillies in this country. They sow when they sow their tomatoes and runner beans, and they run out of summer. UK vegetable planting calendar sets the timing in context, but for chillies, the rule is just “earlier than you think”.
Sowing Chillies and Peppers from Seed
Almost everyone grows chillies and peppers from seed, because the choice of varieties available as seed is enormous compared to the few plants you find at garden centres. Specialist suppliers like Suttons carry a huge range, from mild padrons to the hottest superhots. The seed needs warmth to germinate, and this is where many people come unstuck.
- Sow into small pots or trays of seed compost, about 1cm deep, from late January to early March.
- Provide warmth. Chilli and pepper seed needs 20 to 25°C to germinate reliably. A heated propagator is ideal, or a warm windowsill above a radiator, or an airing cupboard (check daily and move to light the moment they sprout).
- Be patient. Germination takes one to three weeks, sometimes longer for superhots. Erratic germination is normal, do not give up too soon.
- Move to bright light immediately once seedlings appear, or they grow leggy and weak. A sunny windowsill or grow light.
- Pot on into individual pots once seedlings have a couple of true leaves, and keep them somewhere warm and bright as they grow.
The seedlings grow slowly at first and need warmth throughout. A cold windowsill in February will check them badly, so keep them in the warmest bright spot you have. How to grow vegetables from seed in the UK covers the wider seed-sowing technique, much of which applies here.
Where to Grow Them: Greenhouse, Indoors or Outside
This is the big question for UK growers, because our climate is marginal for these heat-loving plants. The honest answer is that where you grow them makes a huge difference to your success, and the warmer you can keep them, the better your crop.
Greenhouse or polytunnel (the best option)
If you have a greenhouse, this is where chillies and peppers do best in the UK. The extra warmth and longer effective season mean bigger plants, more fruit, and reliable ripening even on the hotter varieties. A greenhouse genuinely transforms what is possible with chillies in this country. If you grow tomatoes in a greenhouse, chillies and peppers slot in alongside them perfectly. How to grow tomatoes in the UK covers the greenhouse approach that suits both.
A sunny windowsill or conservatory
No greenhouse? A bright, warm, south-facing windowsill or a conservatory works surprisingly well, especially for compact chilli varieties. Many chillies are happy to spend their whole lives indoors in a pot by a sunny window, and the consistent warmth indoors often beats a cool British summer outdoors. This is genuinely one of the best ways to grow chillies if you have limited outdoor space.
Outdoors (in a good spot and a good summer)
You can grow chillies and peppers outdoors in the UK, but you need to choose carefully and manage expectations. Pick the warmest, sunniest, most sheltered spot you have, ideally against a south-facing wall that radiates heat. Do not put plants outside until all risk of frost has passed, usually late May or early June, and harden them off properly first. How to harden off plants in the UK covers that.
Stick to faster-ripening, milder varieties outdoors. The superhots really need greenhouse warmth to ripen in time. In a good summer, outdoor chillies crop well. In a poor one, you may be picking green chillies in October and ripening them indoors. That is just the reality of the UK climate, and growing some under cover and some outside spreads your bets.
Growing Chillies and Peppers in Pots
Pots are the standard way to grow chillies and peppers in the UK, and for good reason. Containers let you move plants to the warmest spot, bring them under cover when the weather turns, and start them indoors before shifting them out. Almost all my chillies live their lives in pots.
Start seedlings in small pots and pot them on as they grow, finishing in a final pot of around 3 to 5 litres for most chillies, larger for big pepper plants. Do not put a small seedling straight into a huge pot, as the compost stays wet and the roots struggle. Use a good peat-free multipurpose compost. Peat-free compost in the UK and the best compost for vegetables cover what to use, and growing vegetables in pots in the UK and the best vegetables to grow in pots cover the wider container approach.
The advantage of pots is flexibility. A pot of chillies can start on a windowsill, move to a greenhouse, spend high summer on a sunny patio, and come back indoors when autumn arrives to ripen the last fruit. That portability is exactly what these marginal-in-the-UK plants need.
Caring for Chilli and Pepper Plants
Watering
Keep the compost consistently moist but never waterlogged. Chillies and peppers in pots dry out quickly in warm weather and may need daily watering at the height of summer, especially in a greenhouse. Let the surface dry slightly between waterings, and avoid leaving plants sitting in saucers of water. Inconsistent watering, letting plants wilt then drowning them, causes flower drop and problems like blossom end rot on peppers. How often to water plants in the UK covers the principle.
Feeding
Once the first flowers appear, feed every week or two with a high-potassium liquid feed. Tomato feed is perfect and what most growers use, since the same feed that fruits tomatoes also fruits chillies and peppers. Before flowering, a general feed supports leafy growth, but switch to high-potash once flowering starts to drive fruit rather than foliage. Feeding vegetables properly in the UK covers feeding for fruit.
Warmth and pollination
These plants love warmth and need it to set fruit well. In a greenhouse or indoors, where there are fewer insects, give flowering plants a gentle shake or dab the flowers with a soft brush to help pollination. Temperatures that are too low cause flowers to drop without setting fruit, which is another reason warmth matters so much. Protecting garden plants during heatwaves covers the flip side, managing the rare UK days when a greenhouse gets too hot.
Support and pinching out
Taller pepper and chilli plants benefit from a cane for support once they are laden with fruit. Pinching out the growing tip when a young plant is about 20cm tall encourages a bushier plant with more branches and therefore more fruit, though it is optional and many growers skip it. Heavy-cropping plants in particular appreciate staking so the branches do not snap.
Chilli and Pepper Varieties for the UK
Variety choice matters a lot in the UK, because some chillies ripen far faster than others, and the slow superhots can be a real challenge in our short season. The RHS chilli growing guide is a useful second opinion on varieties. Here is an honest guide to what suits UK growing.
- Easy and reliable chillies: Jalapeno, Cayenne, Hungarian Hot Wax and Apache are forgiving, ripen reasonably quickly, and crop well even outdoors in a decent summer. The best starting point for beginners.
- Padron peppers: The Spanish tapas favourite, picked small and green, mostly mild with the occasional hot one. Quick and productive, brilliant for UK growing.
- Sweet (bell) peppers: Reliable in a greenhouse or warm spot. Pick green or wait for them to ripen to red, which takes longer but tastes sweeter. Varieties bred for cooler climates do best.
- Scotch bonnet and habanero: Wonderful flavour and serious heat, but slow to ripen. Really need a greenhouse or a warm indoor spot in the UK, and an early sowing.
- Superhots (Carolina Reaper, Ghost/Naga): Possible but demanding. Sow in January, grow under cover all season, and be patient. A project crop rather than a beginner one.
For your first year, I would genuinely suggest a jalapeno or cayenne for heat, a padron for fun, and a sweet pepper, all of which give a good chance of success. Save the superhots for once you have a season under your belt.
Harvesting Chillies and Peppers
You can pick chillies and peppers at almost any stage, which is part of their charm. Most start green and ripen through to red, yellow, orange or purple depending on the variety, getting sweeter and, in chillies, hotter as they ripen.
Pick sweet peppers green for a fresh, crisp flavour, or leave them to ripen to red for sweetness, knowing that ripening takes longer and the plant produces fewer total fruit as a result. For chillies, picking regularly while green actually encourages the plant to produce more, so a mix of picking some green and letting some ripen works well. Use scissors or secateurs to cut fruit off rather than tugging, which can damage the plant.
At the end of the season, when frost threatens, pick everything, including green fruit. Green chillies will slowly ripen indoors on a windowsill, or you can use them green, and a glut of chillies freezes whole brilliantly or dries well for storage. Few crops give you so much from so few plants. A single productive chilli plant can crop for months and give you more chillies than a household can use fresh.
Overwintering Chilli Plants
Here is something many people do not realise: chilli plants are perennials, and you can keep a plant going for several years. An overwintered chilli starts cropping far earlier the following year, sidestepping the slow early-season growth, which is a real advantage in the UK.
To overwinter, cut the plant back to a short framework of main branches after the final harvest, move it somewhere frost-free and bright (a windowsill, heated greenhouse, or conservatory), and keep it barely watered through winter, just enough to stop it drying out completely. It will look sad and bare, but as the light returns in spring it pushes out fresh growth and gets going weeks ahead of any seedling. Not all plants survive, but the ones that do reward you with an early crop. It is well worth trying with a favourite variety.
Common Chilli and Pepper Problems
- Plenty of flowers but no fruit. Usually too cold for the flowers to set, or poor pollination indoors. Keep plants warm and hand-pollinate flowers with a soft brush.
- Fruit not ripening before autumn. Almost always sown too late, or grown too cool. Sow earlier next year and grow under cover. Pick green fruit and ripen indoors.
- Leggy, weak seedlings. Not enough light after germination. Move to the brightest spot or use a grow light.
- Flowers dropping off. Temperature swings, dryness, or inconsistent watering. Keep conditions warm and steady.
- Aphids and whitefly. Common under cover. Catch early, wash off or use sprays, and encourage natural predators in the greenhouse.
- Blossom end rot on peppers. A dark sunken patch at the base of the fruit, caused by irregular watering. Keep the compost evenly moist.
- Slugs on young plants. They will take seedlings put outside. How to get rid of slugs in the garden covers protection.
Common Questions About Growing Chillies and Peppers
How do you grow chillies in the UK?
Sow chilli seed indoors in warmth (20 to 25°C) between late January and early March, because chillies need a long warm season to ripen. Grow the seedlings on somewhere bright and warm, pot them on as they grow, and keep them in a greenhouse, on a sunny windowsill, or in the warmest sheltered outdoor spot. Feed with high-potassium tomato feed once flowering, and pick fruit from summer into autumn.
When should I sow chilli seeds in the UK?
Sow chilli and pepper seeds indoors between late January and early March. The hotter the variety, the earlier you should sow, as superhots like scotch bonnet and carolina reaper take the longest to ripen. Sowing too late is the single most common reason UK chillies fail to ripen before the cold, so earlier is almost always better.
Can you grow chillies and peppers outdoors in the UK?
Yes, but choose the warmest, sunniest, most sheltered spot, ideally against a south-facing wall, and only put plants out after the last frost in late May or June. Stick to faster-ripening, milder varieties outdoors, as superhots really need greenhouse warmth. In a good summer outdoor chillies crop well; in a poor one you may ripen the last fruit indoors.
Can you grow chillies on a windowsill?
Yes, a bright, warm, south-facing windowsill is one of the best places to grow chillies in the UK, especially compact varieties. Many chillies happily spend their whole lives indoors in a pot by a sunny window, where the consistent warmth often beats a cool British summer outdoors. It is ideal if you have limited outdoor space.
Why are my chillies not fruiting?
The usual causes are cold temperatures preventing the flowers from setting, poor pollination indoors, or too much nitrogen feed pushing leaves over fruit. Keep plants warm, hand-pollinate flowers with a soft brush in a greenhouse or indoors, and switch to a high-potassium feed like tomato feed once flowering begins.
Do you need a greenhouse to grow chillies in the UK?
No, but it helps a great deal, especially for hotter varieties. A greenhouse gives the warmth and longer season that produce bigger crops and reliable ripening. Without one, a sunny windowsill or conservatory works well for many chillies, and milder, faster varieties can crop outdoors in a warm sheltered spot in a good summer.
Can chilli plants survive winter in the UK?
Yes, chilli plants are perennials and can be overwintered. After the final harvest, cut the plant back to a short framework, move it somewhere frost-free and bright, and water it sparingly through winter. Overwintered plants start cropping far earlier the following year. Not all survive, but it is well worth trying with a favourite variety.
A Sensible Place to Start
If you have never grown chillies or peppers, here is the plan. In late winter (January or February), sow seed of an easy variety like jalapeno or cayenne, plus a sweet pepper, into small pots of compost kept at 20 to 25°C on a warm windowsill or in a heated propagator. Move the seedlings to bright light the moment they appear, pot them on as they grow, and keep them warm throughout. Once the frosts pass in late May, settle them in their final pots in the warmest, sunniest spot you have, a greenhouse, conservatory, sunny windowsill, or sheltered patio.
Feed weekly with tomato feed once they flower, keep them warm and evenly watered, and start picking from midsummer. Pick some green, let some ripen, and at the first frost bring everything indoors. Those few plants will give you more chillies than you expect, and if you overwinter your favourite, you will be ahead of the game next year. After twenty years, the early-sowing lesson is still the one I would press hardest: start them sooner than feels sensible, and the UK summer does the rest.
To build a wider warm-crop collection, how to grow tomatoes in the UK and how to grow cucumbers in the UK cover the other greenhouse favourites that grow alongside chillies, how to grow basil from seed in the UK covers the perfect companion herb, and gardening for beginners in the UK covers the wider first-year approach.