How to grow peppers and chillies

The secret to great peppers and chillies is warmth — from sowing through harvest. Give them heat, light and a little feeding once they start fruiting, and they'll deliver far more than you might expect.

Sweet peppers vs chillies — what's the difference?

All peppers and chillies are the same species group, Capsicum annuum and related species. The difference between a sweet bell pepper and a scorching habanero is almost entirely about the concentration of capsaicin — the compound that creates heat. Sweet peppers (bell peppers, frying peppers such as 'Lipstick' or 'Marconi') have little or none; chillies range from mildly warm to extremely fiery.

• Sweet peppers — large, blocky bell peppers; long Italian frying peppers; and small snacking peppers. These take the longest to ripen and produce the largest fruit. They benefit most from a greenhouse or polytunnel in cooler climates.
• Mild chillies — varieties such as 'Anaheim', 'Poblano' and 'Hungarian Hot Wax' are versatile, productive and a good starting point for chilli growing. They ripen relatively quickly and tolerate slightly less warmth than very hot varieties.
• Hot to very hot chillies — 'Cayenne', 'Jalapeño', 'Serrano' and 'Thai Bird's Eye' are among the most widely grown. They are productive and reliable in warm conditions.
• Superhot varieties — Bhut Jolokia (Ghost Pepper), Carolina Reaper, Chocolate Habanero and similar varieties are genuinely challenging to grow well. They need a very long season, maximum warmth and patience. Handle with care and wash hands thoroughly after touching fruit.

For a first attempt, a mild or medium chilli variety or a snacking sweet pepper is a reliable, rewarding choice. They are more forgiving of slightly suboptimal conditions than large bell peppers or extreme superhots.

Starting from seed indoors

Peppers and chillies have one of the longest growing seasons of any vegetable commonly grown in temperate gardens. From seed to first ripe fruit can take five to six months or more for sweet peppers, and even longer for some chilli varieties. This means sowing early is essential — in most cool temperate climates, sowing indoors in late winter or very early spring gives the plant enough time to produce a good harvest before the cold returns.

The key requirement for germination is warmth. Pepper seeds need sustained soil temperatures of around 20–25°C to germinate reliably. Below this, germination becomes slow and erratic; much below 15°C, seeds may simply sit dormant. A heated propagator is the most reliable solution. A warm spot above a radiator, inside an airing cupboard, or on a heat mat can work, but you'll need to move seedlings to light the moment they germinate.

Superhot varieties may need a few extra weeks of warmth before germinating — some growers soak seeds in warm water for several hours before sowing to soften the seed coat and speed things up.

1. Fill small pots or modules with moist seed compost. Use a fine-grade seed compost rather than potting compost. Firm lightly and water so the compost is evenly moist but not saturated.
2. Sow seeds 5 mm deep. Place two or three seeds per pot or module. Pepper seeds are small but not tiny — they're easy to handle individually. Cover with a thin layer of vermiculite or fine compost.
3. Cover and place in warmth. Cover pots with a clear propagator lid or a clear plastic bag to retain moisture. Place in a heated propagator or the warmest spot you have. Check daily and remove the cover as soon as seedlings emerge.
4. Move to the brightest position available. Immediately after germination, seedlings need maximum light to avoid becoming leggy and weak. A bright windowsill, a greenhouse shelf or a grow light are all suitable.
5. Thin to the strongest seedling. Once seedlings have their first pair of true leaves (not the seed leaves), remove the weaker seedlings from each pot by snipping them at soil level with scissors, leaving the strongest one.
6. Keep warm and bright. Pepper seedlings grow slowly at first. Be patient — they're putting down roots. Keep temperatures above 18°C at all times during early growth.

Potting on and growing on

Peppers and chillies need potting on — moving into progressively larger containers — as they grow. Leaving a plant in a pot that's too small stunts growth and reduces fruiting dramatically.

• Move seedlings from their initial small pot into a 9 cm pot once roots start to appear at the drainage holes or the plant looks rootbound.
• From 9 cm, move into a 12–15 cm pot as the plant grows.
• The final pot for most sweet peppers and chillies is 20–30 cm in diameter — this is the container where the plant will spend most of the season and produce its fruit. Very large plants or vigorous varieties may need a slightly bigger pot.
• Use a good-quality peat-free potting compost for the later stages. Add some slow-release fertiliser granules to the compost when potting into the final container, or be prepared to start liquid feeding once the plant begins to grow quickly.
• At each potting-on stage, water the plant thoroughly and allow it to settle for a week or two before any other changes.

Growing position — greenhouse, patio or windowsill

Peppers and chillies are sun-loving, warmth-demanding plants. The more heat and light they receive, the better they grow and the faster their fruit ripens. Choose the warmest, brightest spot you have available.

• Greenhouse or polytunnel: the best option in cool temperate climates. The extended warmth dramatically improves the performance of sweet peppers in particular, and allows a longer growing season at both ends. Ventilate well on hot days — temperatures consistently above 35°C can cause blossom drop.
• Sheltered sunny patio or terrace: works well for chillies and smaller-fruited varieties in a warm summer. A south-facing or west-facing wall creates a heat trap that chillies love. Bring plants indoors if nights drop below about 12–13°C.
• Bright indoor windowsill: surprisingly productive for smaller chilli varieties — 'Apache', 'Demon Red' and similar compact types are sold specifically as windowsill plants. Ensure the pot is large enough and you assist pollination (see below).
• Grow lights: LED grow lights give you the most control and can be very effective, especially for extending the season or growing in a low-light situation. They are increasingly affordable and accessible.

Before moving plants that have been raised indoors to an outdoor or greenhouse position, harden them off gradually over 7–10 days — moving them outside for progressively longer periods during the day before leaving them out overnight.

Watering and feeding for fruit

Once peppers and chillies start to fruit, they become genuinely hungry plants. Getting the feeding and watering balance right during this phase is what separates a mediocre harvest from an excellent one.

• Watering: keep compost consistently moist — never waterlogged, never bone dry. In hot weather, container-grown peppers may need watering daily. Underwatering causes blossom drop and fruit to develop poorly; overwatering causes root problems and can split fruit. Press your finger into the compost: if the top 2 cm is dry, water thoroughly.
• Feeding before flowering: during the early growing phase, a balanced general fertiliser or one slightly higher in nitrogen supports healthy leafy growth and strong stems.
• Feeding once flowering starts: switch to a high-potassium (high-potash) liquid feed such as a tomato fertiliser once you see the first flower buds. Apply weekly or as directed on the product. Potassium promotes flowering and fruit development rather than leafy growth. Continue this right through the season.
• Calcium: peppers can be susceptible to blossom end rot (a dark, sunken patch on the base of the fruit) caused by calcium deficiency — itself usually a result of irregular watering. Consistent moisture is the real solution, but calcium-enriched foliar sprays are available if the problem persists.

Pollination indoors and under cover

Pepper and chilli flowers are self-fertile — each flower contains both male and female parts and can pollinate itself. Outdoors, wind movement and visiting insects do this naturally. Indoors, in a greenhouse or on a windowsill, there is no wind and few or no insects, so the pollen often doesn't move from anther to stigma without help.

Assisting pollination is simple and makes a significant difference to fruit set:

• Gentle shaking: give the plant a gentle shake when flowers are fully open. The vibration dislodges pollen and distributes it within and between flowers. Do this daily when you notice open flowers.
• Soft brush or cotton bud: dab a small, soft artist's brush or a cotton bud into the centre of each open flower and then move to the next. This directly transfers pollen from the anthers (the yellow pollen-bearing parts) to the stigma (the central sticky part).
• Electric toothbrush: some growers use an electric toothbrush held near the base of the flower cluster — the vibration is very effective at releasing pollen. Don't touch the flowers directly.

Open a greenhouse on warm, calm days to allow some natural air movement, and any passing insects will assist. Avoid opening on cold, damp days when sudden temperature drops can stress the plant.

Ripening from green to red

All peppers and most chillies are edible at the green (unripe) stage, and harvesting green is perfectly legitimate — it also encourages the plant to produce more fruit. However, the full flavour, colour and sweetness (or heat, in chillies) develops as the fruit ripens to its final colour: red, orange, yellow, purple or brown, depending on the variety.

Ripening on the plant requires warmth and time. In good summer conditions, fruit can ripen within six to eight weeks of setting for many chilli varieties. Sweet bell peppers take longer and are most reliable in a greenhouse.

If the season ends before fruit has ripened fully — which is common in cooler climates — harvest the remaining green fruit and bring it indoors. Place on a warm, bright windowsill. Chillies especially will continue ripening indoors over several weeks. Some varieties will colour up fully; others may stall at a mid-ripeness stage but still be useful.

Common problems

• Blossom drop: flowers fall before setting fruit. This is the most common pepper problem and has several causes — cold nights, excessive heat, dry air, irregular watering or lack of pollination. Identify the likely cause: if temperature is the issue, protect the plant; if pollination is the issue, assist it manually (see above); if watering is inconsistent, regulate it.
• Fruit not setting after pollination: even after pollination, tiny fruitlets sometimes drop if the plant is stressed. This is usually temperature or watering related. Once conditions stabilise, the plant typically sets fruit successfully.
• Aphids: blackfly and greenfly can colonise pepper plants, clustering on new shoot tips and under leaves. Inspect regularly and deal with infestations early — a strong spray of water knocks them off, or use an insecticidal soap solution. Introducing ladybird larvae or lacewings if you're in a greenhouse is highly effective. See our natural pest control guide for more on managing aphids without chemicals.
• Red spider mite: a common greenhouse pest in hot, dry conditions. Leaves develop a fine mottled, dusty appearance and you may see webbing under leaves. Increasing humidity — misting plants or placing trays of water nearby — helps prevent it. Biological control (predatory mites) is effective in enclosed spaces.
• Leggy seedlings: caused by insufficient light in the early growing stages. Move to a brighter position immediately. A grow light is the most reliable solution when raising seedlings in winter.
• Slow growth: if your plant just sits there for weeks doing nothing, it's almost always too cold. Peppers and chillies genuinely stall in cool conditions. Ensure minimum temperatures are met — above 18°C during the day and above 15°C at night for good growth.

Overwintering chilli plants

One of the most rewarding things about chilli growing is that the plants are perennials in their native warm climates. In a cool temperate garden, frost kills them — but if you bring a chilli plant indoors before the first frost, it can survive the winter in dormancy and return to fruit again next year. An overwintered plant has a huge head start on seedlings and typically produces an earlier, larger crop in its second and subsequent seasons.

How to overwinter a chilli plant:

• Before the first frost, cut the plant back by roughly half to two-thirds — removing most of the leafy growth but leaving a framework of main stems with a few buds.
• Move the pot to a cool, frost-free location — a shed, garage, unheated spare room or similar. The plant needs to go dormant, so a cool spot (around 5–12°C) is better than a warm one.
• Water very sparingly through winter — just enough to prevent the compost from completely drying out, roughly once every three to four weeks. The plant will drop most or all of its remaining leaves; this is normal.
• When you want to bring it back into growth in late winter or early spring, move it back to a warm, bright position and begin watering more regularly. New growth will appear from the cut stems within a few weeks.
• Once new growth is established, pot on into fresh compost if the plant is rootbound and begin feeding as you would a new plant.

Not every overwintered plant survives, but the success rate is high for plants that were vigorous and healthy going into dormancy. It's well worth trying — a two or three year old chilli plant in full production is a spectacular, genuinely productive specimen.

Pepper and chilli checklist

• Sow early — peppers need a long season, so start seeds indoors in late winter or early spring.
• Provide sustained warmth (20–25°C) for germination — a heated propagator is ideal.
• Give seedlings maximum light immediately after germination to prevent legginess.
• Pot on progressively as roots fill each container; don't let plants become rootbound.
• Choose the warmest, brightest growing position available.
• Switch to a high-potassium feed when flowers appear and maintain weekly applications.
• Water consistently — never allow the compost to completely dry out.
• Assist pollination indoors by shaking plants or using a soft brush on open flowers.
• Protect plants from cold nights; bring inside if temperatures drop below 12°C.
• Consider overwintering a favourite chilli plant for a head start next season.