Our detailed growing guide will help you with each step in successfully growing Chilli Peppers.
Growing your own chillies means you can enjoy a huge array of colours, shapes, flavours and levels of heat – a much wider range than you could ever buy in supermarkets. These tender plants grow best in a greenhouse, but can also be grown outdoors in a sunny spot, in pots or in the ground. There’s a wide array of chillies to choose from if you grow your own from seedChillies (Capsicum) are tender plants that need heat, humidity and lots of sunshine to fruit well. Closely related to sweet peppers, they make attractive plants with their colourful, glossy fruits. They grow well in containers and take up little space, with compact varieties reaching only 20–30cm (8–12in) tall. This makes it easy to grow several different varieties, even when space is tight. For the best crop, grow them in a greenhouse, polytunnel or sunny conservatory. They should also be happy in a sheltered, sun-baked spot outdoors – ideally beside a south-facing wall or on a sunny patio or balcony. They generally like similar growing conditions to tomatoes, so are ideal companions. Related RHS GuidesGrowing veg in containersGrowing veg in greenhouses
Buying chilli seeds can be irresistible, with so many colourful varieties and different flavoursThere are hundreds of varieties of chillies too choose from, offering fruits of various colours, shapes and sizes, ranging from mild to unbearably hot. Chilli heat is measured in Scoville Heat Units (SHU), with milder varieties such as ‘Anaheim’ rated at 500–2,500 SHU, ‘Jalapeno’ at 2,500–8,000 SHU, ‘Scotch Bonnet’ at 100,000–350,00 SHU and ‘Carolina Reaper’, one of the world’s hottest chillies, at 2.2 million SHU! Heat is not just dependent on the variety though, it can also vary according to the growing conditions and stage of ripeness. Chilli plants vary in size from as little as 20cm (8in) tall and wide (ideal for a windowsill) up to 60cm (2ft) or more, depending on the variety, so select to suit your growing space. Also look for varieties with an RHS Award of Garden Merit (AGM), which shows they performed particularly well in our trials – check out our list of AGM fruit and veg and our Recommended Varieties below. You’ll also see lots of colourful chillies growing in the veg plots at the RHS gardens over the summer months, so do visit to compare varieties and pick up growing tips.
Chilli seeds are widely available in garden centres and from online seed suppliers. There are also many specialist chilli seed retailers, who offer the widest choice of varieties. Many of these suppliers also sell young plants in spring and early summer. These are handy if you don’t have time to sow seeds or don’t have a suitably warm, bright place indoors to raise good plants. Another option is to buy grafted plants, which are more vigorous so should produce larger crops, and are especially useful if growing conditions are a little cool. They can be ordered from online suppliers for delivery from mid-April. Many retailers also sell chilli plants already in fruit over the summer months.
Sow seeds indoors from late winter to mid-spring – chillies generally need a long growing season, and an early start will give you an earlier and longer harvest. Chilli seeds need warmth to germinate – around 21°C (70°F) – so it’s best to use a heated propagator, although a warm windowsill should be fine too. See our guide below for step-by-step sowing instructions. As soon as your seedlings appear, take them out of the propagator and keep them at 16–18°C (60–64°F) in bright light, and water regularly. When they are 2–3cm (1in) tall, move each one into its own module or small pot of peat-free multi-purpose compost. Then, once roots begin to show through the drainage holes, move them into larger 13cm (5in) pots. Carefully lever out individual seedlings......and replant singly in modules or small pots
Chilli plants can usually cope with a minimum night temperature of 12°C (54°F), but will grow better if kept above 15°C (59°F). However, temperatures over 30°C (86°F) can reduce fruiting, so in hot spells keep the greenhouse well ventilated and put up shading. Chillies prefer a humid atmosphere, so raise the air’s moisture content in warm weather by ‘damping down’ the greenhouse daily – pour a full watering can over the floor, then leave it to evaporate.
Water little and often to keep the soil or potting compost evenly moist, avoiding waterlogging and drought. Flower buds may fall off if plants get too dry. Also add mulch to help hold moisture in the soil. Plants in containers can dry out very quickly in summer, so check the compost regularly – see our video guide to watering efficiently.
Feed chilli plants with a high potassium liquid fertiliser weekly, as soon as flowering starts. Related RHS GuidesLooking after plants in containersHow and what to feed plants
To encourage side-shoots, which should carry more fruit, pinch out the shoot tips once plants reach 30cm (1ft) tall. Large plants and those in growing bags may need support. Use several canes per plant, and take care when tying in the stems, as they can be brittle.
When growing in a greenhouse, you can usually keep picking chillies well into autumnChillies are generally ready for harvesting from mid-summer into autumn if grown in a greenhouse. Fruiting outdoors should start by August. Towards the end of the season, bring plants indoors if possible, to help the remaining fruits develop. You can also use grow lights to extend the cropping season indoors – see our video guide below for tips.
Harvested chillies can be easily dried or frozen, so you can enjoy your crop through the winter too.
Chillies usually crop best in a greenhouse – when grown outdoors, fruiting may be reduced, especially in cooler summers. Several sap-sucking insects can cause problems, particularly in a greenhouse, so check plants regularly – see below for details. Young chilli plants also need protection from slugs and snails. Related RHS GuidesControlling problems without chemicalsPreventing problems
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