Overview
What chillies need, when they crop, and whether they suit your space.
Chillies crop well in a pot, from mild ‘Anaheim’ to fiery ‘Scotch Bonnet’. They need two things: time and heat. Sow from late winter, because the season is long. Give plants your warmest, sunniest spot: a greenhouse, a south-facing patio or a windowsill. Then pick often, and they keep flowering.
Quick facts
- Botanical name
- Capsicum annuum
- Soil pH
- 6.0 – 6.5
- Feeding
- Moderate feeder
- Temperature
- 21 – 29 °C
- Hardiness
- USDA zone 12a and warmer
- Time to harvest
- 70 – 120 days
- Height
- Up to 120 cm (47 in)
- Propagation
- Seed
Optimal growth
Keep above 12 °C
Growing details
- Spacing
- 45 cm (18 in)
- Frost sensitivity
- Frost tender
Growing calendar
- Start indoors: 8 to 12 weeks before your last frost
- Transplant: May, June
- Harvest: July, August, September, October
UMD: 8 to 10 weeks before the last frost, 12 for some types. After the last frost, once the soil is warm. See When to sow and plant. Under glass from midsummer into autumn; outdoors from August.
Is this plant right for you?
- Great in pots
- Windowsill varieties
- Needs warmth
- Long season
- Greenhouse favourite
- Ornamental fruit
- Frost tender
Good to know
Plan for support early: this plant needs a stake, cage or frame once it gets going. Keep it above 12 °C (54 °F): frost kills it.
Before You Grow
Choose a variety for the heat you like and the space you have, and the warmest spot you can offer.
Compact varieties, 20 to 30 cm (8 to 12 in) tall, fit a windowsill and crop just as well.
What you need
Seed or young plants
Specialist seed suppliers have the widest choice. See choose your chillies.
A heated propagator
Seeds need about 21 °C (70 °F) to germinate. A warm windowsill works, later. See sowing.
Pots in three sizes
Modules or 7.5 cm (3 in) pots, then 13 cm (5 in), then a final 22 to 30 cm (9 to 12 in) pot. See containers.
Peat-free multi-purpose compost
For every stage after sowing.
High-potash liquid feed
Tomato feed is fine. See feeding.
Canes and soft ties
For taller varieties; stems are brittle. See pinching and support.
Choose your chillies
There are hundreds of varieties, from mild to extremely hot. Choose for heat, for plant size, and for how much warmth you can give.
Heat is measured in Scoville Heat Units (SHU). The heat sits in the pale placenta that holds the seeds, not the seeds themselves (Iowa State). It varies with growing conditions as well as variety.
Species. Most garden chillies are Capsicum annuum: jalapeño, cayenne, serrano, Anaheim. C. chinense gives habanero and Scotch bonnet; C. baccatum the aji chillies of Peru; C. pubescens hot chillies with black seeds.
Size. Plants range from 20 cm (8 in) tall and wide, ideal for a windowsill, to 60 cm (2 ft) or more (RHS); UMD’s peppers reach 90 to 120 cm (3 to 4 ft).
Warmth. The hottest varieties, such as ‘Bhut Jolokia’, grow slowly and need heat and humidity: grow them indoors. Tough, compact types such as ‘Apache’ cope outdoors.
Grafted plants are more vigorous and crop more, which helps where summers are cool (RHS).
Chilli heat compared
-
‘Anaheim’
- Heat (SHU)
- 500 to 2,500
- Species
- C. annuum
- Notes
- Mild, long fruits
-
Jalapeño
- Heat (SHU)
- 2,500 to 8,000
- Species
- C. annuum
- Notes
- Pick green, or when it turns black-green
-
Cayenne
- Heat (SHU)
- 30,000 to 50,000
- Species
- C. annuum
- Notes
- Long, tapering; good for drying
-
‘Scotch Bonnet’
- Heat (SHU)
- 100,000 to 350,000
- Species
- C. chinense
- Notes
- Needs warmth and a long season
-
‘Carolina Reaper’
- Heat (SHU)
- Up to about 2.2 million
- Species
- C. chinense
- Notes
- One of the hottest; grow indoors
Figures from the RHS and Clemson. The same variety can be milder or hotter depending on how it is grown.
Where chillies grow best
Chillies are tender plants that need heat, humidity and lots of sun. They crop best in a greenhouse, polytunnel or conservatory, and compact varieties do well on a sunny windowsill.
Outdoors in a mild area, give them your warmest, most sheltered spot: a sunny patio or beside a south-facing wall (RHS).
Temperature. They grow best at 21 to 29 °C (70 to 85 °F) by day (Iowa State, Clemson). They cope with nights down to about 12 °C (54 °F), but grow better above 15 °C (59 °F) (RHS). Frost kills them.
Too hot. Above about 30 °C (86 °F), fruiting falls off; ventilate and shade a greenhouse in hot spells (RHS).
Sun. Full sun: at least six hours a day, and more is better; UMD prefers eight to ten. In very hot, sunny climates, a little late-afternoon shade keeps plants setting fruit (UMD).
Humidity. Chillies like moist air. In a greenhouse, damp down the floor daily in warm weather.
- Best growth
- 21 to 29 °C (70 to 85 °F) by day
- Minimum at night
- About 12 °C (54 °F); better above 15 °C (59 °F)
- Fruiting falls off
- Above about 30 °C (86 °F)
Soil and compost
In pots, use peat-free multi-purpose compost. In the ground, chillies want fertile, well-drained soil that holds moisture.
Preparation. On poor or heavy soil, dig in a few bucketfuls of garden compost or well-rotted manure before planting (RHS). Chillies do poorly in heavy, wet soil: use a raised bed where drainage is poor (Utah State).
pH. 6.0 to 6.5 (Clemson).
Warmth. Warm the soil under cloches for a couple of weeks before planting (RHS); UMD finds plants set into soil below 18 °C (65 °F) just sit there.
Rotation. Don’t follow tomatoes, potatoes, aubergines or other peppers: Clemson waits three years.
Planting
Sow early in warmth, pot on in stages, and plant out only when nights stay warm.
Chillies need a long season: the hottest varieties want sowing as early as January.
When to sow and plant chillies
Sow early: chillies need a long season, and an early start gives an earlier and longer harvest.
Sow indoors 8 to 10 weeks before your last frost, or 12 for some types (UMD). In the UK that means late winter to mid-spring (RHS): from January with a heated propagator and grow light, from March without (Gardeners’ World). Sow the hottest varieties first: they are slowest.
Plant into a greenhouse once it stays warm, usually from late May in the UK.
Plant outdoors after all risk of frost, once nights reliably stay at or above 12 °C (54 °F): usually late May or early June in mild parts of the UK. Harden plants off over two to three weeks first.
Late start. Buy young plants in spring instead; this also suits super-hot varieties.
- Sow from January with bottom heat, March without.
- Plant out when nights stay at or above 12 °C (54 °F).
- Harden off over 2 to 3 weeks.
How to grow chillies from seed
Warmth to germinate, then bright light and steady potting on.
-
Sow in warmth
Cover the seed lightly with moist peat-free compost; Utah State sows about 13 mm (½ in) deep. Keep at about 21 °C (70 °F) in a heated propagator; Utah State germinates at up to 27 °C (80 °F).
-
Give strong light
Once seedlings are up, grow them on at 16 to 18 °C (60 to 64 °F) and keep the compost evenly moist (RHS). They need bright light or they turn leggy. On a late-winter windowsill, add a grow light: Utah State hangs it 5 to 8 cm (2 to 3 in) above them for 14 to 16 hours a day.
-
Prick out
At 2 to 3 cm (1 in) tall, or when the first true leaves appear, move each into its own module or 7.5 cm (3 in) pot.
-
Pot on
When roots show through the drainage holes, move them into 13 cm (5 in) pots.
-
Keep them warm
Indoors, usually until at least late May, before planting into a final pot or bed.
How to plant out chillies
Into a final pot, a greenhouse border or a warm bed outside.
-
Harden off
Over two to three weeks, outside by day and in at night, if they are going outdoors.
-
Choose the final home
A large pot, a greenhouse border or a warm bed. See containers for pot sizes.
-
Plant at the same depth
As they were growing in their pots.
-
Space them out
38 to 45 cm (15 to 18 in) apart in the ground, or 30 cm (1 ft) for dwarf varieties (RHS).
-
Add support
Push in a cane for taller varieties now, before the roots spread.
-
Protect them outdoors
Cover young plants with cloches against wind and cold, ideally until the end of June (RHS).
Care
Even moisture, a weekly high-potash feed once flowers open, and help with pollination indoors.
Flowers drop when plants go dry or temperatures swing. Steady conditions give steady fruit.
Care by growth stage
Young plants
Warmth: 16 to 18 °C (60 to 64 °F) · Light: as much as possible
Keep them warm and bright; pot on as roots fill. See sowing.
Growing on
Water: keep evenly moist
Pinch out if you want bushier plants; stake tall ones. See pinching and support.
Flowering
Feed: high-potash, weekly · Humidity: damp down or mist
Start weekly feeding and help pollination indoors. See flowers and fruit set.
Fruiting
Water: daily in hot weather in pots
Pick often to keep new flowers coming. See harvesting.
End of season
Overwinter: warm, bright, dry
Bring pots indoors to ripen the last fruits, or overwinter the plant. See pinching and support.
Watering chillies
Chillies need a steady supply of moisture to grow and crop well: keep the compost or soil evenly moist, neither soaked nor dry.
In pots. They dry out quickly in summer. Check often and be ready to water daily in hot, dry weather (RHS).
In the ground. About 2.5 cm (1 in) a week (Iowa State); Utah State, in a dry climate, gives 2.5 to 5 cm (1 to 2 in). Water deeply, so the soil is moist at least 15 cm (6 in) down (Clemson), and mulch to hold moisture.
When it matters most. From flowering through fruit development. Dry spells make flower buds drop, and uneven watering causes blossom end rot.
Humidity. In hot weather, mist plants or damp down the greenhouse: it also deters red spider mite.
Feeding chillies
In pots, feed weekly with a high-potassium liquid feed, such as tomato feed, as soon as flowering starts (RHS, Gardeners’ World).
In rich soil, plants may need no regular feeding, though it can boost the yield (RHS). US extensions side-dress with a little nitrogen after the first fruits set.
Not too much nitrogen. Too much gives big, leafy plants with few flowers and delays fruiting (Clemson, Utah State).
Underfeeding and heat. Gardeners’ World reports a grower who makes fruits hotter by underfeeding and underwatering. The plants are weaker and the crop smaller.
Pinching, support and overwintering
Pinching out. Not needed for a good crop. Pinching the growing tip at about 20 to 30 cm (8 to 12 in) tall gives a bushier plant and, the RHS finds, a bigger crop of smaller fruits, but it can delay fruiting.
Support. Stems are brittle. Tie taller plants and those in growing bags to several canes, gently (RHS), or use a small cage.
Overwintering. Chillies are perennials, and a plant kept over winter gives a head start next year. In autumn, cut it back to a manageable size, keep it in a warm, bright place such as a windowsill or conservatory, and water sparingly (RHS).
Flowers and fruit set
Chilli flowers have male and female parts, so each can set fruit on its own. Outdoors, insects and wind move the pollen.
Indoors, with no insects or wind, flowers may drop unless you pollinate them by hand (Gardeners’ World): brush inside each open flower with a small paintbrush, or tap the stems.
Temperature. Fruit won’t set when nights fall below about 13 °C (55 °F) or days go above 32 °C (90 °F) (Utah State). NMSU finds flowers drop when nights stay above 24 °C (75 °F). Hot peppers set fruit in warmer weather than sweet peppers (Iowa State).
Other causes of flower drop are drying out, overwatering, overfeeding and swinging temperatures. The problem usually passes as the weather settles.
Chillies in containers
Chillies grow well in pots and take up little space, so you can grow several varieties even on a balcony.
Pot size. Sources differ with plant size: the RHS grows one plant per 22 cm (9 in) pot, Gardeners’ World moves bigger plants into 30 cm (12 in) pots, and UMD’s minimum for peppers is 19 litres (5 US gallons). Compact chillies manage in the smaller pots. Use peat-free multi-purpose compost.
Position. A sunny, sheltered patio or a greenhouse. Pots can come indoors on cold nights and at the end of the season.
Care. Water whenever the compost starts to dry, daily in hot weather, and feed weekly from flowering.
Growing chillies indoors
Compact varieties crop well on a sunny windowsill, and the hottest ones often do best indoors.
Light. Your sunniest window, ideally south-facing.
Pollination. Hand-pollinate open flowers. See flowers and fruit set.
Pests. Aphids, whitefly and red spider mite spread fast indoors. Check under the leaves regularly, and mist in dry, warm rooms.
Ripening. A sunny windowsill also finishes off fruits on plants brought in at the end of summer.
Problems
Flower drop, blossom end rot and sap-sucking pests are the usual troubles.
Common chilli problems
Most are growing problems, and most come back to temperature or water.
Flowers dropping without fruit
- Pollination
- Temperature
- Water
No pollinators indoors, nights too cold or too warm, or dry compost. See flowers and fruit set.
Dark, leathery patch at the fruit tip
- Blossom end rot
Calcium not reaching the fruit, from uneven watering, drought or too much nitrogen. Keep moisture even and mulch.
Pale, papery patch on the side of fruits
- Sunscald
Fruit exposed to strong sun in hot, dry weather. Plants with good leaf cover suffer less.
Lots of leaves, few flowers
- Too much nitrogen
Overfeeding with nitrogen. Switch to a high-potash feed (Clemson).
Plants not growing after planting out
- Cold
Cold soil or nights. UMD finds plants in soil below 18 °C (65 °F) just sit there. Wait for warmth, or use cloches.
Twisted, cupped new leaves
- Weedkiller
Often drift from lawn weedkiller, or grass clippings from a treated lawn used as mulch (Utah State).
More problems with chili peppers
Common pests
Aphids
Soft green or black insects under the leaves, which curl and turn sticky. They can spread viruses. Squash or wash them off, or use insecticidal soap.
Glasshouse red spider mite
Mottled leaves, fine webbing and early leaf fall, worst in hot, dry air. Mist plants and damp down.
Glasshouse whitefly
Small white insects that fly up when disturbed and leave sticky honeydew. Check plants under glass regularly.
Thrips
Tiny insects that attack seedlings and can spread viruses (NMSU, Clemson). Check new growth and flowers, especially under glass.
Caterpillars
Chew leaves and bore into fruits outdoors. Pick them off by hand; for heavy attacks Clemson uses Bacillus thuringiensis (Bt), a biological insecticide for caterpillars. Follow the label.
Flea beetles
Tiny black beetles that chew small holes in seedlings outdoors and can thin a sowing (NMSU, Utah State).
More problems with chili peppers
Common diseases
Grey mould (botrytis)
Fuzzy grey mould on stems, leaves and fruits in damp greenhouses. Remove dead material promptly, ventilate, and don’t crowd plants.
Bacterial leaf spot
Small, water-soaked spots on leaves that turn brown, in warm, wet weather. Avoid overhead watering and use clean seed.
Viruses
Mottled, curled, stunted leaves and misshapen fruits. Spread by aphids and by hands that have handled tobacco. Remove infected plants.
Wilts and root rots
Plants wilt from the bottom and may die, often in wet or waterlogged soil. Don’t overwater, and rotate crops.
More problems with chili peppers
Harvest & Use
Pick green for a bigger crop or red for more flavour, then dry, freeze or pickle the surplus.
Harvesting chillies
Most chillies are ready 70 to 85 days after planting out; habaneros take 90 to 120 (UMD). Under glass, picking starts in midsummer; outdoors, by August.
Green or ripe. Every chilli can be picked green or left to colour. Green is milder; ripe is richer and hotter. Fruits take 35 to 45 days from flower to full colour (Utah State).
Ready fruit is firm, plump and smooth-skinned (Utah State).
For the biggest crop, pick early fruits green: leaving them to ripen on the plant slows new flowering and gives a much smaller harvest. Let the late ones ripen on the plant (RHS).
How. Cut the stalks with scissors or a knife: stems are brittle and break if you pull.
End of season. Bring pots indoors to ripen the last fruits, or pull whole plants before frost and hang them somewhere warm (UMD).
- Pick green early on for a bigger crop.
- Cut, don’t pull.
- Let the last fruits ripen on the plant.
Storing and using chillies
Fresh. Clemson and Iowa State store peppers at 7 to 10 °C (45 to 50 °F) for two to three weeks. Utah State prefers 10 to 13 °C (50 to 55 °F) for one to two weeks, warning that long spells in a cold fridge cause chilling injury.
Drying. Ripe chillies dry well. Spread them on a rack, or thread them on a string through the stalks, and leave in a warm, airy place for several weeks. Store in an airtight jar in a cool, dark place, or crush into flakes.
Freezing and pickling. Freeze whole or chopped, or pickle in vinegar.
Cooking. For less heat, scrape out the pale placenta that holds the seeds.
Propagation
Saving seed from your own plants, and when it comes true.
Saving chilli seed
Chillies are grown from seed, and you can save your own from ripe fruit.
Choose a fully ripe, well-coloured fruit from a healthy plant of an open-pollinated variety. F1 hybrids are crosses of two parent lines, so their seedlings differ from the parent.
Cross-pollination. Insects can cross varieties and even species. UMD advises screening plants from insects, or separating varieties by 150 m (500 ft), for seed that comes true.
Collect and dry. Scrape the seeds onto a plate and leave them until fully dry. Store them somewhere cool and dry.
Sweet and hot side by side? Crossing affects only the seed, not this year’s fruit: sweet peppers next to hot ones won’t turn hot (UMD).
More to Explore
Quick answers, guides that pair well with chillies, and the sources behind this one.
Frequently asked questions
When should I sow chilli seeds?
8 to 10 weeks before your last frost; in the UK, from January with bottom heat or March without. See when to sow and plant.
Why are my chilli flowers falling off?
No pollinators indoors, temperatures too cold or too hot, dry or soggy compost, or overfeeding. See flowers and fruit set.
Can I grow chillies indoors?
Yes: compact varieties crop well on a sunny windowsill. See growing indoors.
Can chillies grow outside?
In a warm, sheltered, sunny spot, once nights stay at or above 12 °C (54 °F). They crop more reliably under glass.
How big a pot does a chilli need?
From 22 cm (9 in) for compact varieties; bigger plants want 30 cm (12 in) or more. See containers.
Should I pinch out chillies?
It isn’t needed, but it gives a bushier plant. See pinching and support.
Are green chillies ripe?
They are edible but not fully ripe. See harvesting.
Do chillies get hotter as they ripen?
Yes, and hot, dry growing conditions add heat. See harvesting.
Can I keep my chilli plant over winter?
Yes: cut it back and keep it warm, bright and on the dry side. See overwintering.
Will hot and sweet peppers cross in my garden?
Only in the seed. This year’s fruits keep their own flavour.
Related guides
Sources
- How to grow chilli peppers (opens in a new tab) Royal Horticultural Society
- Growing chiles in New Mexico (opens in a new tab) New Mexico State University
- Growing peppers in the home garden (opens in a new tab) Iowa State University Extension and Outreach
- Pepper (opens in a new tab) Clemson Cooperative Extension
- Peppers in the garden (opens in a new tab) Utah State University Extension
- Growing peppers in a home garden (opens in a new tab) University of Maryland Extension
- How to grow chillies (opens in a new tab) BBC Gardeners’ World