RHS Growing Guides
How to grow sweet peppers
Our detailed growing guide will help you with each step in successfully growing Peppers.
Getting Started
Homegrown peppers are a delicious summertime treat
Closely related to chillies, they make attractive plants with their colourful, glossy fruits, which ripen from mid-summer to early autumn. They also take up little space, usually reaching only about 60cm (2ft) tall and 30cm (1ft) wide, and grow well in large pots.
Month by Month
| J | F | M | A | M | J | J | A | S | O | N | D | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sow | ||||||||||||
| Plant | ||||||||||||
| Harvest |
Choosing
Grow a few different varieties for a colourful, varied harvest
Some varieties are more suitable for outdoor cropping than others. Larger fruits take longer to grow and ripen, so if you’ll be planting outdoors, with a shorter growing season, it’s best to choose a variety with smaller fruits. You’ll also find several dwarf or compact varieties, ideal for containers on a sunny patio or balcony, or even a kitchen windowsill.
When choosing, look in particular for varieties with an RHS Award of Garden Merit (AGM), which should grow and crop reliably – see our list of AGM fruit and veg (135kB pdf) and our Recommended Varieties below. You’ll also find sweet peppers growing in the veg areas at the RHS gardens over the summer months, so do visit to compare varieties and pick up growing tips.
What and where to buy
Sweet pepper seeds are widely available in garden centres and from online seed suppliers. Many also sell young plants in spring and early summer. These are ideal if you don’t have a suitably warm, bright place to raise good plants, or just want a few. Grafted plants may also be available – these are more vigorous and should crop more reliably in cooler growing conditions. They can be ordered from online suppliers for delivery from mid-spring.
Recommended Varieties
Mid-season variety with large fruits ripening from cream to yellow. Plant grows to 60cm tall.
Large, tapering fruits up to 25cm long. Sweet flavour, crisp texture and thin skin.
Square-shaped, fleshy fruits, 12cm long, with mild, sweet flavour.
Sowing
Sow sweet pepper seeds indoors from mid-February to early March for plants that are to be grown under glass, and in late March or early April for growing outdoors. To germinate, they need 18–21°C (65–70°F), so after sowing, place in a heated propagator, if available, or on a warm windowsill. Once the seedlings appear, keep at 16–18°C (60–64°F) in bright light and water to keep the compost evenly moist. When seedlings have two true leaves, move them into their own 7.5–9cm (3–3.5in) pot, maintaining a high temperature to encourage good growth.
For step-by-step sowing instructions, see our guides below.
Planting
Give sweet pepper plants plenty of light and warmth – they grow best above 15°C (59°F)
Sweet peppers will grow and crop best in a greenhouse, polytunnel, conservatory or coldframe. In very warm, sheltered locations, you can plant them outside too, once overnight temperatures are reliably above 12°C (54°F). However, they are likely to produce fewer fruits outdoors, and the shorter growing season means the fruits may struggle to ripen before temperatures start to drop in early autumn. Before planting outside, carefully harden off your plants for a couple of weeks, to acclimatise them to outdoor conditions. Give them your warmest, sunniest spot, ideally on a sunny patio or beside a south-facing wall, with temperatures of 15°C (59°F) or more. Plant them in their new location at the same level they were previously growing in their pot, and add canes to support taller varieties.
Planting in containers
Plant your young peppers into their final container in late April if growing in a heated greenhouse, mid-May in an unheated greenhouse, or late May/June if growing outside. Choose a container at least 30cm (1ft) wide and fill with peat-free multi-purpose compost, planting one pepper in the centre. Alternatively, plant two or three in a standard growing bag. Add canes to keep the plants stable and upright.
Planting in the ground
Choose a spot with well-drained, fertile, moisture-retentive soil. If your soil is poor or very heavy, dig in a few bucketfuls of organic matter, such as garden compost or well-rotted manure, before planting. Alternatively, if you practise no-dig, mulch the soil ahead of planting directly into the mulch. Warm the soil with cloches for a couple of weeks before planting so plants get off to a strong start. Space sweet pepper plants 38–45cm (15–18in) apart, depending on the variety. Compact varieties can be spaced 30cm (1ft) apart. Cover young plants with cloches to provide wind and cold protection, preferably until the end of June.
Plant Care
Temperature and humidity
Sweet peppers can cope with a minimum night temperature of 12°C (54°F), but will grow better if kept above 15°C (59°F). However they don't like to be too hot – temperatures over 30°C (86°F) can reduce fruiting, so keep the greenhouse well-ventilated and put up shading in summer.
Peppers also like high humidity, so add moisture to the air in warm weather by ‘damping down’ the greenhouse regularly – pour a full watering can over the floor, leaving it to evaporate during the heat of the day.
Watering
Sweet peppers need a steady supply of water to grow and crop well, so water as needed, aiming to keep the soil or potting compost evenly moist. Flower buds may fall off if plants get too dry. Plants in containers can dry out very quickly in summer, so check the compost regularly and be prepared to water daily in hot, dry weather.
If you are growing your pepper plants in the ground, mulch the soil with a thick layer of organic matter to help reduce moisture loss.
Feeding
Feed pepper plants in containers with an organic, high potassium, liquid fertiliser weekly, as soon as flowering starts. Plants growing in enriched soil may not need regular feeding, but doing so can help to boost yield.
Pruning and Training
Pinching out the growing tips of pepper plants is not usually needed to ensure a good crop, but can be done once plants reach around 30cm (1ft) tall to produce a bigger crop of smaller fruits. Be aware that pinching out can delay fruiting.
Support each plant with a sturdy bamboo cane, tying in the main stem as it grows. If plants produce a heavy crop of large peppers, more support may be needed as the stems can be quite brittle and snap easily. Insert bamboo canes around the plant and attach the fruit-laden side-shoots using soft twine.
Harvesting
Harvest sweet peppers regularly, to encourage further fruiting
Towards the end of the season, cover outdoor plants with plastic-free fleece or bring potted plants indoors, to help the remaining fruits ripen.
Problems
Aphids are attracted to sweet pepper plants, so check shoot tips and under leaves regularly to prevent colonies getting established. Several other sap-sucking insects can be problematic too, especially in a greenhouse and in dry conditions.
Get involved
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