Capsicum annum

Common name: Sweet Peppers

Sweet peppers can range in colours from green to yellow to red depending on the stage of ripeness.

Similarly they can come in various shapes, sizes for example; carrot shaped, bell shaped or block shaped.

They can be eaten cooked in stews, stir fries and or raw in salads.

They are not fully hardy and should therefor should only be grown outdoors in the south and west of the UK. i.e. in areas where the temperature does not drop below 12°-15°C (55°-60°F)

In the cooler northern areas, they can be stood outside in pots during the summer and brought indoors when the weather becomes much cooler.

Otherwise, plant them out 600mm (24") apart in a cool Greenhouse border,Tunnel, Growbags, Large pots or Ring Culture.


Growing in a Tunnel


Growing by the Ring Culture method

Depending upon variety, they will grow to a height of 750mm (30")

Aim for a minimum night temperature 15 °C (60 °F), and avoid temperatures above 30°C (85°F) under glass, by providing maximum ventilation.

Avoid starting pepper plants too early in the spring this practice can lead to leggy plants that may never fully recover.

Pests and Diseases:


The main three pests that can affect sweet peppers are thrips, whitefly and red spider mite, all of which can be controlled biologically or by proprietary insecticides.

Regular misting will deter spider mite, and aid fruit set.


Aphids, snails and slugs can be troublesome.

As with tomatoes, peppers are sensitive to temperature fluctuations, which can cause bud drop or poor fruit set.

Similarly, irregular watering or dry compost can cause blossom end rot.

Affected fruits show a leathery pale brown patch at their base, pick off affected fruits to encourage new flowers.

Adequate staking to support the heavy fruit is important to avoid branches breaking, particularly with plants grown outside that are subject to winds.


Week 12: Sow seeds in pots / trays of seed compost and germinate at a temperature of 21°C (70°F)

Germination should take around 7-10 days.

Week 14: When the seedlings are large enough to handle, prick them out individually into 75mm (3") pots of potting compost.


Saved Seeds


Seeds Germinated


Pricked Out



Week 18: If planting out is delayed perhaps because of the weather, pot up plants into 125mm (5") pots rather than letting them becoming potbound in the smaller pot.

Week 21-22: Plant out in a sheltered border or into 250mm (10") pots or two or three plants per grow bag after all danger of frost has passed.

Cover plants with fleece or cloches, or coldframe until plants are established.

Alternatively, plant them out 600mm (24") apart in a cool greenhouse border, growbags and / or large pots.

Pinch out growing tips* when plants reach 300mm (12”) tall to induce more fruiting branches.

* This task is optional, i.e. with some of the taller varieties this may not be required due the amount of fruit they produce naturally.

Encouraging plants to produce more fruit may give you the desired quantity at the expense of quality.

The reverse is generally true for low growing varieties.

Support tall varieties.

Water little and often, avoid water-logging and equally avoid drought.

In hot weather plants may need watering twice a day.

Maintain high humidity in greenhouses by damping down once or twice a day in hot weather, this will also help to keep whitefly at bay.

Spray the leaves daily with water during the flowering period to assist fruit setting.

From Week 27: give a dilute liquid feed (potash) at two week intervals when the embryo fruits appear.

Continue feeding up until the fruit changes colour.

If grown under glass, lightly shade the glass during the hottest months.

The fruits should be ready for picking in September / October depending upon variety and season.

The fruit will change colour if left on the plants and develop a sweeter flavour, although this may reduce the yield by 25 percent or more, and the skins may become a bit tougher.

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