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Pepper

Sweet or hot, a pepper plant crops for months in warm weather and does well in a pot on a sunny balcony.

1. Sow indoors 8 to 10 weeks before your last frost, 5 mm deep, at a steady 21 to 28 C. Peppers germinate slowly and unevenly.
2. Use a heat mat or the top of a fridge. Below 18 C the seed may not come up at all.
3. Pot on into 9 cm pots at the first true leaves and keep them in the brightest place you have.
4. Harden off over ten days and plant out only once nights stay above 12 C.
5. Plant at the same depth as in the pot, 45 cm apart, and stake each plant at planting time.
6. Pinch out the first flower that appears at the main fork so the plant builds a frame first.
7. Feed weekly with a high potash tomato feed from the moment fruits start to swell.
8. Pick the first few peppers green to keep the plant producing, then let later ones colour up.

Soil

Free-draining, fertile soil at pH 6 to 6.8 with compost worked in. They hate heavy wet clay.

Sun

Full sun, eight hours. Peppers need warmth above all: below 15 C at night they simply stop.

Water

Even and moderate, 2 to 3 litres per plant every two or three days in hot weather, at the base. Wet leaves and soggy roots both invite rot.

Spacing

45 cm apart, rows 60 cm apart

Depth

5 mm deep for seed. Unlike tomatoes, plant at the same depth they grew in the pot.

Care

['Keep them warm. A cloche, fleece or a greenhouse in cooler zones roughly doubles the crop.', 'Tie the main stems to a cane, since a loaded pepper plant snaps at the fork.', 'Water evenly, because irregular watering causes blossom end rot just as it does in tomatoes.', 'Mist or tap the flowers to help pollination in still air under cover.', 'In extreme summer heat give afternoon shade, because fruit sitting in 40 C sun scalds white.']

Harvesting

Cut, never pull, leaving 2 cm of stalk, because the branches snap easily. Green peppers can be picked as soon as they are full size and glossy. Leaving them to turn red, yellow or orange takes two to four weeks more, roughly doubles the vitamin C and the sweetness, and reduces the total number of fruits.

Storing

Fresh peppers keep one to two weeks in the fridge. Sweet peppers freeze well raw, sliced and bagged, with no blanching needed. Chillies dry beautifully: thread them on a string in a warm airy place, or use a dehydrator at 50 to 60 C, then grind or store whole. Roasted peppers keep in oil in the fridge for a week, but never store them in oil at room temperature because of the botulism risk.

Grow it next to

Good with basil, onions, carrots, spinach and marigolds. Keep away from fennel, and from beans which shade them. Do not follow potatoes, tomatoes or aubergines in the same bed.

Problems

[{'cause': 'Too cold. Peppers stall below about 15 C and sulk', 'fix': 'Wait for warm nights before planting out, use a cloche or fleece, and grow against a sunny wall. Nothing else will fix a cold pepper.', 'symptom': 'Plants sit and do nothing for weeks after planting out'}, {'cause': 'Nights below 13 C, days above 35 C, or very dry air', 'fix': 'Shade during heat waves, ventilate under cover, and water evenly. Setting restarts when the temperature returns to range.', 'symptom': 'Flowers drop off without setting'}, {'cause': 'Sunscald, where fruit is exposed to intense direct sun with little leaf cover', 'fix': 'Do not over-prune the leaves, and use 30 percent shade netting in heat waves. Scalded fruit is safe to eat if you cut the patch out.', 'symptom': 'Pale papery sunken patches on the sun-facing side of the fruit'}, {'cause': 'Blossom end rot from irregular watering', 'fix': 'Water evenly and mulch. In containers this almost always means the pot dried out at some point.', 'symptom': 'A dark sunken patch at the base of the fruit'}, {'cause': 'Red spider mite, which thrives in hot dry still air', 'fix': 'Raise humidity by damping the floor, improve ventilation, hose the leaf undersides, and remove the worst leaves.', 'symptom': 'Stippled pale leaves with fine webbing, mainly under cover'}]

Saving your own seed

Easy for sweet peppers, which mostly self-pollinate, though chillies cross readily with other peppers within 150 m and the result can be unexpectedly hot. Let the fruit colour fully and start to wrinkle, scrape out the seed, dry it on a plate for a week, and store cool. Wear gloves with hot varieties.

Containers

One of the best container crops. A 20 to 25 litre pot per plant, 30 cm deep, on the sunniest wall you have. The reflected heat from a wall or balcony floor genuinely improves the crop.