Growing Chillies from Seed
Chillies need a long growing season — start seeds indoors in January or February for the best results in the UK.
When to sow
Sow seeds between January and March. Chillies need a long season — aim for at least 16 weeks between sowing and your last expected frost date (typically mid-May in most of the UK).
Sowing in January gives the most time, but requires supplementary light (a grow light or very bright south-facing window) to prevent weak, leggy seedlings in the low light of midwinter.
Germination
Temperature: 25–30°C
Soil temperature matters more than air temperature. A heated propagator is the most reliable way to achieve this. Without heat, germination can take weeks or fail entirely.
Humidity
Keep the compost consistently moist but not soggy. Cover with a propagator lid or a clear plastic bag until seeds sprout.
Darkness until sprout
Seeds do not need light to germinate — cover them. Once the first seedlings emerge, remove the cover and move immediately to your brightest light source.
Germination kit
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Potting on
- 1First pot (9 cm): transplant when the first true leaves appear (the pair after the cotyledons). Use seed compost — fine grade with low nutrients suits small seedlings. Hold by the leaf, never the stem.
- 21 L pot: pot on when roots begin to circle the bottom of the 9 cm pot. Switch to a general purpose compost or a chilli-specific mix with good drainage.
- 3Final pot (3–10 L): pot on before hardening off. Larger pots give larger plants and more fruit — a 10 L container is a good target for outdoor growing. Add perlite to improve drainage if using standard compost.
Potting up
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Hardening off
Hardening off is the process of gradually acclimatising indoor-raised plants to outdoor conditions. Move them outside too quickly and leaves will scorch or the plant will wilt badly.
Spend 7–14 days gradually increasing outdoor exposure: start with a few hours in a sheltered, semi-shaded spot. Each day, increase the time and move to a slightly more exposed position. After two weeks, plants should tolerate a full day outdoors.
Pinching out
When the main stem reaches 20–30 cm, pinch out the growing tip above a leaf node. The plant will respond by sending out two side shoots from that node, creating a bushier shape with more fruiting branches.
You can repeat this process on the side shoots once they reach a similar size. Each pinch delays fruit production slightly but significantly increases the total number of fruits at harvest.
Noticed something wrong with your seedlings? ChilliScan can diagnose nutrient deficiencies, pests, and other problems from a photo.
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