RHS Growing Guides
How to grow sweet peppers
Our detailed growing guide will help you with each step in successfully growing Peppers.
Getting Started
With their colourful fruits, sweet peppers are a vibrant and attractive crop. Also known as bell peppers or pointed peppers, depending on the fruit shape, these tender plants are best grown in a greenhouse, but can also be planted outdoors in a sunny spot, in pots or in the ground.
Peppers can be picked at any stage – when green and crunchy or when riper and sweeter
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
Jobs to do now
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Choosing
Compact varieties such as ‘Mohawk’ are ideal for growing in containers
Some varieties are more suitable for outdoor cropping than others. Larger fruits take longer to grow and ripen, so if you’ll be planting them 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 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 plants. 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
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 at least 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 late summer. 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 to grow outside. Choose a container at least 30cm (1ft) wide, and use peat-free multi-purpose compost, or plant two or three in a standard growing bag. Add canes to keep the plants stable and upright. See our guides below for more tips.
Planting in the ground
Choose a spot with well-drained, fertile, moisture-retentive soil that is ideally slightly acidic. To achieve this, dig in moderate amounts of well-rotted manure, at a rate of 5.4kg (10lb) per square metre/yard, but avoid using fresh manure or large quantities, as this can lead to lush, leafy growth at the expense of fruit. Next, warm the soil with cloches for a couple of weeks before planting. Space sweet pepper plants 38–45cm (15–18in) apart, depending on the variety. Compact varieties can be spaced 30cm (1ft) apart. Then cover young plants with cloches to provide wind 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). But 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 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
Water regularly to keep the potting compost or soil evenly moist, ensuring plants neither dry out nor get waterlogged. They may shed their flower buds if they run short of water. Also apply mulch to damp soil to help retain moisture around the roots. Plants in containers may need watering daily in summer, as the compost will dry out quickly.
Feeding
To encourage fruiting, feed sweet pepper plants once a week with a high-potassium liquid fertiliser, once flowering starts.
Pruning and Training
Pinch out the tip of the main stem when plants reach about 30cm (1ft) tall, to encourage side-shoots to form, which should lead to more fruit. You can also pinch out the tips of the resulting side-shoots if you want more but smaller fruits.
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
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. See below for details. Young pepper plants also need protection from slugs and snails.
Get involved
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