Chilli pepper
Capsicum annuum
The most practical fruiting crop for an indoor grower in Britain. Chillies are compact, self-fertile, happy in a pot on a sunny sill, and — unlike almost every other fruiting vegetable — genuinely worth growing without a greenhouse. Kept frost-free over winter, a plant will crop for several years.
- Position
- Full sun
- Water
- moderate demand
- Drainage
- Free-draining
- Grows to
- 30–90 cm × 30–45 cm
- Hardiness
- H1C
- Harvest
- July to October
- Difficulty
- Some care needed
Described view
A chilli plant carrying fruit at three stages on the same plant at once — green, part-coloured and fully ripe — with the compact woody habit and small pointed leaves visible behind them
August
Harvest
Chilli pepper’s year
Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.
| Activity | J | F | M | A | M | J | J | A | S | O | N | D |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sow under cover | February. | |||||||||||
| Plant out | May. | |||||||||||
| Harvest | July. | August. | September. | October. |
Names that cause confusion
chilli — Several Capsicum species are grown as chillies. Most common cultivars are C. annuum; habaneros and scotch bonnets are C. chinense and need more heat and a longer season again.
Timing that travels
The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.
- Sow under cover9–12 weeks before your last spring frost
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Chillies — sowing
Checked 2026-08-13
The hotter, slower species need the earliest start of any common crop — January or February in Britain.
- Plant out — Greenhouse2–4 weeks after your last spring frost
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Chillies — growing on
Checked 2026-08-13
Conditions it needs
- Light
- Full sun
- Direct sun
- 6 hours a day or more
- Frost
- Frost tender
- Hardiness rating
- H1c (RHS)
- Grows best at
- 20–30 °C
- Germinates at
- 21–30 °C
- Soil
- Peat-free compost, Loam
- Soil pH
- 6–7
- Drainage
- Free-draining
- Water needs
- moderate
- Drought
- moderate tolerance
- Waterlogging
- poor tolerance
- Heat
- good tolerance
- Wind and exposure
- poor tolerance
Where these figures come from
- LightSourced guidancehigh confidence
- Royal Horticultural Society: Grow your own: chillies
Checked 2026-08-13
- Direct sunHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- FrostSourced guidancehigh confidence
- Royal Horticultural Society: Chillies — hardiness
Checked 2026-08-13
- Hardiness ratingSourced guidancehigh confidence
- Royal Horticultural Society: RHS hardiness ratings
Checked 2026-08-13
- Grows best atSourced guidancehigh confidence
- Home and Garden Information Center — Clemson Cooperative Extension: Peppers — culture
Checked 2026-08-13
- Germinates atSourced guidancehigh confidence
- OSU Extension Service — Oregon State University: Vegetable seed germination temperatures
Checked 2026-08-13
- SoilHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Soil pHHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- DrainageHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Water needsHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- DroughtHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- WaterloggingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- HeatHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Wind and exposureHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
On your soil
Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.
| Soil | Verdict | Why |
|---|---|---|
| Heavy clay | Works, with one condition | Chilli pepper will crop on heavy clay, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
| Sandy | Grows well here | Chilli pepper grows perfectly well on sandy without special measures, though it is not the soil it would choose. |
| Chalky and alkaline | Works, with one condition | Chilli pepper will crop on chalky and alkaline, but one thing has to be dealt with first. The soil is substantially too alkaline for it: it wants pH 6 to 7, and this soil sits around 7.8 to 8.5.The pH is the obstacle. Small shifts are achievable and slow; large ones are not. On chalky and alkaline the dependable answer is a container of the right compost rather than an attempt to change the ground. |
| Loam | Prefers this soil | Loam suits Chilli pepper as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering. |
| Silty | Prefers this soil | Silty suits Chilli pepper as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. The free drainage is exactly what it wants. The soil holds moisture, which saves a great deal of watering. |
| Peaty and acid | Works, with one condition | Chilli pepper will crop on peaty and acid, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
| Shallow over rock | Prefers this soil | Shallow over rock suits Chilli pepper as it stands: The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting. |
| Made ground and urban soil | Works, with one condition | Chilli pepper will crop on made ground and urban soil, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse. |
Not sure which you have? Four hand tests will settle it.
Space and spacing
- Mature height
- 30–90 cm
- Mature spread
- 30–45 cm
- Rooting depth
- 30 cm
- Spacing
- 40–45 cm apart
Where these figures come from
- Mature heightHorticultural consensusmoderate confidence
Varies enormously by cultivar: compact ornamental types stay under 30 cm, some C. chinense reach well over a metre.
No external citation — see the evidence type above.
Checked 2026-08-13
- Mature spreadHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Rooting depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- SpacingSourced guidancehigh confidence
- Royal Horticultural Society: Chillies — spacing
Checked 2026-08-13
In a container
- Minimum volume
- 5–10 litres
- Minimum depth
- 20 cm
Where the container figures come from
- Minimum volumeSourced guidancehigh confidence
- Royal Horticultural Society: Chillies in containers
Checked 2026-08-13
- Minimum depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
Compact cultivars crop well in surprisingly small pots — a 5-litre pot on a sunny sill is a real crop, not a token one.
Where and how you can grow it
Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.
| Method | Suitability | What it needs |
|---|---|---|
| Windowsill | Well suitedsourceSourced guidancehigh confidence
Checked 2026-08-13 | A south or west-facing sill; A compact cultivarThe standout indoor edible: compact, self-fertile, and it fruits in the conditions a house actually provides. |
| Greenhouse | Well suitedsourceSourced guidancehigh confidence
Checked 2026-08-13 | |
| Polytunnel | Well suitedsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Container | Well suitedsourceSourced guidancehigh confidence
Checked 2026-08-13 | A warm sheltered spot outdoors, moved under cover in autumn |
| Hydroponics | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Grow tent | WorkablesourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Aquaponics | WorkablesourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Open ground | MarginalsourceGrowingHQ editorial positionmoderate confidence Some quick-maturing cultivars ripen outdoors in a good southern summer. Most do not.
Checked 2026-08-13 |
Growing it
- SowingSow in a heated propagator at 21–30 °C. Below about 18 °C germination is slow and patchy, and this is the commonest reason chilli seed is written off as dead when it is merely cold.
- ProtectionBring plants indoors before the first frost and keep them barely moist and above about 10 °C. They lose their leaves and look dead; most start again in spring and crop earlier than a new sowing.
- PollinationSelf-fertile. Indoors, a gentle tap on the stem while the flowers are open sets fruit reliably.
- WateringWater regularly but let the surface dry slightly between waterings — chillies dislike sitting wet and are among the easiest plants to kill by kindness in a cold spring. Once fruit has set, a slightly drier plant produces hotter fruit, which is one of the few places where stress is useful.
- FeedingFeed weekly with a high-potassium tomato feed once the first fruits have set. Before flowering a balanced feed is enough; too much nitrogen gives a tall leafy plant with very few pods.
Where this guidance comes from
- SowingSourced guidancehigh confidence
- OSU Extension Service — Oregon State University: Vegetable seed germination temperatures
Checked 2026-08-13
- ProtectionHorticultural consensusmoderate confidence
- Royal Horticultural Society: Overwintering chilli plants
Checked 2026-08-13
- PollinationHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- WateringSourced guidancemoderate confidence
- Royal Horticultural Society: Chillies — watering
Checked 2026-08-13
- FeedingSourced guidancehigh confidence
- Royal Horticultural Society: Chillies — feeding
Checked 2026-08-13
Is it worth putting under cover?
Whether it will grow there is on the methods table above. This is whether the space is well spent, which is a different question and usually the one being asked.
| Structure | What protection is worth | What decides it |
|---|---|---|
| Greenhouse | Only possible under coversourceGrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file.
Checked 2026-08-13 | Ripening heat, with the same mechanism as sweet pepper and slightly more tolerance — the small hot cultivars are the ones with a chance outdoors. |
| Polytunnel | Extends the seasonsourceGrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file.
Checked 2026-08-13 | Overnight temperature. Glass holds overnight heat that polythene loses, so a tunnel runs cooler at night than a greenhouse in the same garden. For a crop at the edge of its heat requirement that difference decides whether the fruit ripens. |
Growing it without soil
Nearly anything can be grown in a soilless system by somebody with enough equipment. The useful question is whether it is worth it, in which technique, and what goes wrong.
An established soilless crop. Grown this way commercially or routinely by home growers, with predictable results.
source
Sourced guidancemoderate confidence
- Purdue Extension — Purdue University: Greenhouse pepper production
Checked 2026-08-13
The most practical fruiting crop for a small indoor system: compact, self-fertile and productive for its size.
Techniques that suit it
- Drip-fed mediumSolution is dripped into an inert medium around each plant. The most forgiving technique and the one that suits large, long-season, heavy crops.
- Deep water cultureRoots hang in aerated solution. Very productive and very unforgiving of solution temperature — warm solution holds less oxygen and root disease follows.
- Ebb and flowA bed of inert medium floods and drains on a timer. The medium holds moisture between floods, which makes it far more tolerant of interruption than NFT.
source
Horticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Root space
- Modest — compact cultivars have a small root system and suit smaller systems than a tomato needs.
- Lighting
- Needs supplementary light
- pH band
- 5.5–6.5
Where these figures come from
- Root spaceHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- LightingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- pH bandSourced guidancehigh confidence
Outside roughly this band, individual nutrients become unavailable even when they are present in the solution — which is why a crop can starve in a full reservoir.
- Purdue Extension — Purdue University: Hydroponic solution management — pH
Checked 2026-08-13
What actually goes wrong
- pH drift. The solution moves as the plants take nutrients up, and by the time deficiency symptoms appear on the leaves the cause is several weeks old.
source
Sourced guidancehigh confidence
- Purdue Extension — Purdue University: Hydroponic solution management — pH
Checked 2026-08-13
- Pump or power failure. In nutrient film and aeroponics there is no reserve at the roots, so a crop can be lost within hours; medium-based systems hold moisture and are far more forgiving.
source
Sourced guidancehigh confidence
- Purdue Extension — Purdue University: Hydroponic system design — failure modes
Checked 2026-08-13
No nutrient recipes here
GrowingHQ records pH bands, which are measurable properties of nutrient availability, and deliberately records no EC or PPM targets and no mixing instructions. Published targets vary by cultivar, growth stage, water source and technique, and the figures that apply to your system are on the product you bought.
Harvesting
- When it is readyFruit can be picked green or left to colour. Heat generally increases as the fruit ripens and continues to develop for a few days after colouring.
- How to pick itCut with scissors, leaving a short stalk.
- Keeping itThin-walled cultivars air-dry well on a string. Thick-walled ones do not and are better frozen whole.
Where the harvest guidance comes from
- When it is readySourced guidancehigh confidence
- Royal Horticultural Society: Chillies — harvesting
Checked 2026-08-13
- How to pick itHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Keeping itHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
Keep picking
What goes wrong
| Problem | How often | Notes |
|---|---|---|
| Natural fruit colouring | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | Whole cultivar groups darken before they redden. Firm flesh under the patch is the test. |
| Blossom drop | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | |
| Aphids | commonsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 | Very common on indoor and greenhouse plants. |
| Blossom end rot | occasionalsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 |
Grown with, grown after, grown instead
Every relationship states its mechanism. A pairing nobody can explain is a pairing nobody has checked, and it does not go in.
- Closely relatedSweet pepperThe same species as most sweet peppers, differing in capsaicin production. Sowing, feeding and overwintering guidance transfers between them without adjustment.
source
Sourced guidancehigh confidence
- Plants of the World Online — Royal Botanic Gardens, Kew: Capsicum annuum
Checked 2026-08-13
Safety and edibility
- Contact hazardchildrenCapsaicin from cut fruit stays on the skin and transfers readily to eyes and other sensitive areas, where it causes intense burning that water does not relieve. The hottest cultivars can blister skin on prolonged contact.
source
Horticultural consensushigh confidence
- Royal Horticultural Society: Chillies — handling
Checked 2026-08-13
Wear gloves when cutting hot cultivars, keep hands away from the face, and wash with soap rather than water alone. Milk or oil removes capsaicin better than water.
Sources for this page
GrowingHQ editorial synthesis · Home and Garden Information Center · OSU Extension Service · Purdue Extension · Royal Horticultural Society
Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-13.
If something is wrong with it
- Dark sunken patch at the bottom of a fruit — 3 causes GrowingHQ holds for chilli pepper
- Flowers dropping without setting fruit — 2 causes GrowingHQ holds for chilli pepper
- Leaves rolling or curling inwards — 3 causes GrowingHQ holds for chilli pepper
- Lower leaves turning yellow — 2 causes GrowingHQ holds for chilli pepper
Something else? Work through it with the diagnostic tool.