How to Grow Chillies & Peppers from Seed (Capsicum annuum & chinense)

Chillies and peppers have the longest run-up of anything in the vegetable garden. A tomato sown in March is cropping by July; a habanero sown in March can still be green when the first frost arrives. That one fact — how long a Capsicum needs from seed to ripe pod — decides almost everything: when to sow, how warm to keep the seed, which varieties suit a patio pot and which need a greenhouse, and why the hottest ones go in first.

With the last pods colouring up now, this is the moment to plan: decide which chillies to dry, which plants to overwinter, and which seeds to have ready for January. This guide covers the whole cycle, from the first warm tray to the last picking.

• Botanical name Capsicum annuum, C. chinense, C. baccatum and C. frutescens — tender perennials grown as annuals
• Sow indoors January–February for habaneros and superhots · February–April for most chillies and sweet peppers
• Germination 25–28 °C in the compost · 7–14 days for annuum, up to 3–4 weeks for chinense
• Harvest July–October · green pods any time, full colour and heat weeks later

Four species, four timetables

Every chilli and sweet pepper in our range belongs to one of four species, and the botanical name on the packet tells you how early to sow and how long the season will be.

• Capsicum annuum — the big, quick group: bell peppers such as California Wonder, pointed sweet peppers like Corno Rosso, Padrón and Friggitello, and the everyday chillies — jalapeño, serrano, cayenne, Fresno, Hungarian Yellow Wax. See the Capsicum annuum collection.
• Capsicum chinense — the fruity, fiercely hot group: habanero, Scotch bonnet, Madame Jeanette, Bhut Jolokia, Dorset Naga and Carolina Reaper, plus the gentle Brazilian Biquinho. Slow to germinate, slow to ripen. See the Capsicum chinense collection.
• Capsicum baccatum — the South American ajís, tall plants with citrusy pods; ours is Hot Lemon Drop. A long season, but a little more forgiving of cool nights.
• Capsicum frutescens — small upright pods held above the leaves, the bird's-eye group; ours is the Indonesian Rawit mix, bushy and happy in a pot.

Sweet or hot is not a species difference — a bell pepper and a cayenne are both annuum. Heat comes from capsaicin, made in the pale ribs inside the pod, which is why cutting out the pith cools a chilli far more than scraping out the seeds.

When to sow: the hotter, the earlier

Work backwards from the harvest. Quick annuum chillies need two to three months from planting out to the first ripe pod, bell peppers several weeks more to turn red, and the chinense superhots a hundred days or more from flower to ripe fruit. In a northern summer that leaves little slack:

• January–February: C. chinense and C. baccatum. Madame Jeanette, Dorset Pink and Lombardo are among the peppers tagged for a January sowing.
• February–March: most chillies and sweet peppers — the main window on our vegetable sowing calendar and the bulk of the February sowing range.
• March–April: quick types for pots and sheltered beds — Padrón, jalapeño, compact Redskin F1 and Calabrese Compact, and the snacking minis.

The catch with January is light, not warmth. A propagator will germinate the seed, but the seedlings then face eight- or nine-hour days — below the ten hours a plant needs to grow rather than merely survive (see the 10-hour daylight rule). Sow in January only if you can offer a grow light or a very bright south-facing sill; otherwise a mid-February sowing catches up surprisingly fast.

How to sow chillies and peppers, step by step

1. Sow shallow in fine compost Two or three seeds per small pot or module, 5 mm deep, in moist seed compost, covered with a thin layer of compost or vermiculite.
2. Give bottom heat of 25–28 °C The step that matters. At room temperature chillies come up slowly and patchily; in a heated propagator or on a heat mat they appear in a week or two. Keep the lid on — more in how to germinate seeds.
3. Be patient with chinense Habaneros and superhots can take three to four weeks. Do not give up on a tray inside a month; just check it has not dried out.
4. Full light the day they emerge Lid off, brightest spot you have, and about 20–22 °C by day, no lower than 16 °C at night. Warmth plus poor light is the recipe for leggy seedlings.
5. Thin, then pot on Keep the strongest seedling. At the first true leaves, move it to a 9 cm pot at the same depth — peppers do not root along the stem the way tomatoes do. Hold seedlings by a leaf, never the stem.
6. Pot on in stages, plant out late A 1–2 litre pot when roots show, then the final home — a 5–10 litre pot, a growbag with two or three plants, or a greenhouse border — as flower buds form. Outdoors only once nights stay above 10 °C and the plants are hardened off.

Growing on: pinching and the crown flower

Young peppers grow slowly until the days lengthen in March; what matters is that they stay short and sturdy. Turn windowsill pots daily and keep the compost just moist — peppers mind wet roots far more than a brief dry spell.

Two small interventions make a real difference. On bushy chilli varieties, pinch out the growing tip at about 20 cm; the plant branches from below and carries more pods on a sturdier frame. On sweet peppers, leave the tip but remove the first flower in the fork of the main stem — the crown or king flower. Left on, it pulls the plant into fruiting before it has built enough leaf; taken off, it gives a bigger plant and a heavier crop. Pepper stems are brittle, so tie the main stem to a cane (plant supports).

Flowers, fruit set and feeding

Pepper flowers are self-fertile, so a single plant sets fruit on its own; under glass, a gentle tap on the stems around midday helps the pollen move. The problem growers actually meet is flower drop — blossoms that yellow and fall. The usual causes are nights below about 15 °C, days above 30 °C in a closed greenhouse, very dry air or erratic watering: ventilate, damp down on hot days and water consistently.

Once the first flowers open, switch to a high-potash tomato feed every week or two (feeding and fertilising); too much nitrogen gives a lush bush with few pods. Check growing tips for aphids weekly, especially under glass in spring (common garden pests).

Harvesting — and the end of the season

Every pepper is edible green; green simply means unripe. Picking the first fruits green encourages the plant to set more, so take early pods green and let later ones colour. Heat builds as the pod ripens — which is also why Padróns picked small are nearly all mild, and more of them turn hot the longer they hang. Cut pods with scissors rather than pulling; the branches snap easily.

By late September, as nights fall towards 10 °C, the outdoor season is over. Pick everything worth having and decide whether a favourite plant — especially a slow chinense — is worth keeping: overwintered plants fruit four to six weeks earlier next summer. The rest can go with the other summer crops; our guide on how to put the vegetable garden to bed covers what to clear and what to leave. For your own seed, use a fully ripe pod of an open-pollinated variety — peppers cross when varieties flower side by side — and follow our step-by-step guide to saving chilli and pepper seeds; heirloom vs F1 explains which varieties come true.

Common mistakes

• Sowing on a cool windowsill. Without bottom heat the seed sits for weeks and often rots. The compost needs 25–28 °C, not the room.
• Sowing early without the light to match. January sowings on a dim sill stretch, stall and are overtaken by February sowings.
• Giving up on habaneros too soon. Three to four weeks is normal for C. chinense.
• Jumping straight into a big pot. A small rootball in cold, wet compost sulks. Pot on in stages.
• Planting out in early May. One cold night checks a pepper for weeks.

Frequently asked questions

Can I sow chillies in September or October?
Not for a crop: days are already near ten hours and shortening, and an autumn seedling is overtaken by a February sowing. The one exception in our range is the dwarf ornamental pepper mix, a pot plant tagged for sowing into October — expect slow growth until February without a grow light. For an early crop next year, overwinter a plant instead.

Why haven't my pepper seeds germinated?
Usually the compost is too cold — below about 20 °C germination crawls. Other causes: sowing too deep, compost drying out under the lid, and old seed. Pepper seed keeps less well than tomato seed; two to three years is a safe rule, and our guide to how long seeds last includes a germination test.

Can I grow peppers outdoors?
Yes, in a warm, sunny, sheltered spot from June, with quick varieties: Padrón, jalapeño, cayenne, Hungarian Yellow Wax, Redskin F1 and Rawit. Large bells and chinense types rarely ripen outdoors in a cool summer. Pots help, because you can move them into the sun — see container gardening from seed and our container-friendly vegetables.

How hot are the different chillies?
In Scoville heat units (SHU), roughly: Biquinho and most Padróns are mild; jalapeño 2,500–8,000; cayenne 30,000–50,000; habanero, Scotch bonnet and Madame Jeanette 100,000–350,000; Bhut Jolokia, Dorset Naga and Carolina Reaper past a million. Growing conditions shift the numbers, but not the ranking.

Peppers reward the gardener who starts early, keeps the seed warm and the seedlings bright, and lets the pods ripen. For the basics that apply to every crop, see our beginner's guide to growing vegetables from seed. Then browse the full chilli and pepper range, the hot Capsicum chinense varieties, organic Padrón and cayenne among our organic seeds, the tomatoes that share the windowsill in spring, the wider vegetable collection and our growing guides library.