Our detailed growing guide will help you with each step in successfully growing Peppers.
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 sweeterSweet peppers (Capsicum) are tender and need lots of sun and consistent warmth to crop well, so are usually grown under cover in the UK, in a greenhouse, polytunnel, conservatory or coldframe. They are only really successful outdoors in milder parts of the country or in long, hot summers, and benefit greatly from cloche or fleece protection. Wherever you’re ultimately going to grow them, they need to be sown in warmth indoors, from late winter to early spring. 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. Related RHS GuidesGrowing veg in containersGrowing veg in greenhouses
Compact varieties such as ‘Mohawk’ are ideal for growing in containersThere are many varieties of sweet pepper, with fruits of various shapes, sizes and colours, from wide and rounded to long and pointed, large or small, in shades of green, bright red, orange, yellow and purple. They are also called bell peppers or pointed peppers, depending on the shape of the fruits. Long, pointed peppers are generally sweeter and have a thinner skin than rounded bell peppers. 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.
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.
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 regularly. When they have two true leaves, move them into their own 7.5–9cm (3–3.5in) pot, maintaining a high temperature to encourage growth. For step-by-step sowing instructions, see our guides below.
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.
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.
To encourage fruiting, feed sweet pepper plants once a week with a high-potassium liquid fertiliser, once flowering starts. Related RHS GuidesChoosing fertilisersLooking after plants in potsGrowing veg in pots
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.
Harvest sweet peppers regularly, to encourage further fruitingIn a greenhouse, sweet peppers can be harvested from mid-summer into autumn. Outdoors, they will start fruiting later, usually in August, and finish earlier, once temperatures start to drop in late summer or early autumn. Pick as required when the fruits are swollen and glossy. Most sweet peppers ripen from green to red, but some varieties turn yellow, orange or purple. The fruits get sweeter as they ripen. You can harvest your peppers at whichever colour and stage of maturity you prefer, but bear in mind that leaving fruits on the plant to ripen fully will hinder further fruit development. Towards the end of the season, cover outdoor plants with fleece or bring potted plants indoors, to help the remaining fruits ripen. You can use grow lights to extend the cropping season indoors – see our video guide below for tips. Related RHS GuidesVideo – using grow lights indoors
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. Related RHS GuidesControlling problems without chemicalsPreventing problems
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