How to grow chillies Keep your cool and a hot harvest is well within reach

GROWING chillies is all the rage. They need hardly any space, look attractive and can give you all the heat you need in the kitchen. Although the Central and South American plants come from much warmer climes, they’ll produce a crop in Scotland. If I can get a decent harvest at 200m above sea level in the Borders, they’ll thrive in most places.

Chillies are short-lived perennials that, with care, can even be nursed through a Scottish winter to produce better harvests in later years. Simply bring the plants into the warmest feasible part of the house. Chillies hibernate over winter so they need some but not much water. And warmth is luckily more important than sunlight. The leaves will probably drop and you may want to cut the plant back to around 15cm, but it should burst into life next spring, when light becomes every bit as important as heat. I also find the peppers keep ripening on the window sill well into autumn.

The challenge just now is keeping the plants growing well so the fruits swell and ripen. For a good crop, put chillies in a greenhouse or, in a milder part of Scotland, a polytunnel. You’ll be guaranteed failure if you try growing them outdoors because they do need a minimum daytime temperature of 18C, with no less than 12C overnight. A humid atmosphere and all the available sun are essential for best results.

How much you feed and water chillies depends on how hot you want them to be. As with all plants, too much water produces larger fruits with less flavour. So, with chillies, less water leads to spicier fruit.

In Scotland we can’t manipulate the spiciness as much as we could in the south of England because sun and temperature levels are much lower, but we can get slightly hotter chillies with reduced watering. The general rule of thumb is to keep the compost moist, but not soggy, and water every tw or three days, increasing this to daily in the sunniest weather.

Be careful not to use a general-purpose nitrogen-rich liquid feed as this encourages vigorous, leafy growth, rather than flowering and fruiting. An overfed plant just produces leaves, but a very slightly stressed one needs to flower and set seed as soon as it can.

Chillies are normally grown in pots so begin feeding them once the flowers start to form. As with tomatoes and cucumbers, use a feed rich in potassium. Homemade liquid comfrey is best as well as being free, but a general-purpose organic tomato feed also does the job. Feed once a week. Again, overfeeding discourages flowering.

If flowers form and then drop, they haven’t been pollinated by bees or other insects. This can easily happen when the plants are being grown on a window sill. Prevent this by hand-pollinating with a small artist’s paint brush. Insert the brush into a flower, twirl it then move on to the other flowers, thereby mimicking a bee, to encourage germination.

The two main pests are red spider mite and aphids. If your greenhouse is humid, red spider mite is less likely, but you can use a biological control if necessary.

Aphids are all too common in a greenhouse, where there are fewer of the natural predators than in the garden. Thumb squashing is the simplest method. When watering, check the underside of the leaves and rub any sap suckers into oblivion. You could use insecticidal soap, but only sparingly and with care because chilli peppers can be easily damaged by the insecticide.

PHOTOGRAPH: SHUTTERSTOCK/ P-FOTOGRAPHY Shun nitrogen-rich liquid feeds if you want chillies with fruits rather than vigorous leaf growth, using ones high in potassium instead Chillies range from fairly mild – for use as a standard vegetable – to intensely hot (to be used sparingly as a fiery spice). They come in many colours, becoming hotter as they mature.Mild varieties include: Padron, a small, bullet-shaped, very mild green variety; Trinidad Perfume, which is golden and slightly aromatic with a citrussy flavour; and Chilaca, which is slightly stronger and dark brown with a flavour almost like black pepper.The best-known medium-to-hot chilli is jalapeno, which is best left until fully ripened. And if your tastes veer towards the very spicy you could try Ring of Fire, a cayenne-type chilli best left until deep red and fully ripe, and Carolina Reaper, a recent introduction which is widely claimed to be the hottest of all chillies.For help and growing advice pop into The Chillilicious Farm, Ceres, Fife, between noon and 5pm on Fridays, Saturdays and Sundays. Established last year, Scotland’s first chilli farm also has a shop, a visitor centre and a chilli tunnel containing many unusual varieties. Visit chillilicious.co.uk.