Sowing chillies: how to grow hot and flavourful gems from seed
Chillies are not only hot – they’re true heat lovers! Both the seeds for germination and the plants for fruit development need plenty of warmth. If you want to grow chillies from seed, it’s important to choose the right location. By the way: sweet peppers, which are botanically mild chilli varieties, benefit from similar growing conditions. Both belong to the nightshade family and are heavy feeders, with chillies requiring significantly more heat than, for example, tomatoes.
When is the best time to sow chillies?
That depends on the variety and your local climate. A good rule of thumb: the hotter the chilli, the longer it takes to ripen – which means you should start sowing earlier. The ideal time for starting seeds indoors is from mid-February to late March, either on a sunny windowsill or in a heated propagator.
1. Germination Temperature: Keeping It Warm Enough
Chilli seeds germinate best at a consistent +25–28°C. Use a heat mat or place a mini propagator on a radiator to maintain warmth.
Important: After germination (around 2 weeks), reduce the temperature to +20–22°C to encourage strong, healthy plants.
2. Artificial Light for Strong Seedlings
Once the seeds have sprouted, chillies need 12–16 hours of light per day. LED grow lights help keep the seedlings compact and robust.
3. Best Time to Sow
Start seeds indoors 8–10 weeks before the last frost date – usually between mid-February and late March in temperate climates.
4. Potting On
Once the first true leaves have fully developed (after 2–3 weeks), pot the seedlings on. Trim the roots slightly to promote healthy growth.
5. Planting Out
From mid-May to early June, after the last night frosts, you can plant chillies outdoors. Gradually harden them off over several days and water well after transplanting.
6. Soil and Location
Chillies thrive in loose, well-draining soil rich in humus. Avoid waterlogging, but do not let the soil dry out completely. In temperate UK climates, they grow best in a greenhouse. Outdoors, choose the warmest, most sheltered spot or use protective fleece.
7. Feeding and Watering
As heavy feeders, chillies need nutrient-rich soil and plenty of water. Regular feeding – for example with comfrey or nettle tea – is essential for strong growth and fruiting.
Chillies belong to the genus Capsicum and are divided into five main species – each with its own unique traits:
- Capsicum annuum: The most common species, including bell peppers, Jalapeños, Cayenne and many Thai chillies. Great for beginners – high-yielding and versatile, ranging from mild to extremely hot.
- Capsicum baccatum: South American Ají types with a fruity, floral aroma (e.g. Aji Amarillo, Lemon Drop). These plants can exceed 2 metres in height and need plenty of space.
- Capsicum chinense: Home to the world’s hottest chillies (e.g. Habanero, Bhut Jolokia). Thin-walled, aromatic fruits that require tropical growing conditions.
- Capsicum frutescens: Compact, upright-growing types like Tabasco or Thai chillies – perfect for containers and balconies. The heat is intense but short-lasting.
- Capsicum pubescens: Exotic Rocoto chillies with black seeds and hairy leaves. These are perennial, hardy down to -5°C, with a uniquely spicy flavour.
How Big Do Chilli Plants Grow?
Tiny seeds can grow into large chilli bushes up to two metres tall. But there are also compact varieties, ideal for growing in pots on the balcony or windowsill.
Why Grow Chillies from Seed?
Growing chillies from seed is not only rewarding – it's also sustainable. Discover rare varieties that aren’t available in shops and enjoy watching fiery fruits grow from tiny seeds. Whether you're a beginner or an experienced gardener, these tips will help ensure a successful chilli-growing season!
