Nigel Parker says that providing you follow a few key rules, you shouldn’t go far wrong. Here, he discusses the dos and don’ts and shares some top tips for growing chillies…

How hot should you go?

“Don’t underestimate the heat,” Parker warns. “Often people grow types that are too hot for them. A jalapeño is around 6,000-8000 Scoville units, the measuring scale of heat.

“A habanero can be 30 times hotter than a jalapeño. So when you say something is ‘a bit hotter’, people don’t realise it’s a significant jump.

“Extremes include as the 7 Pot group – including 7 Pot Jonah – which are really hot, and then you have the ghost chillies such as the bhut jolokia, which are running at a million Scoville units.”

And if you want something milder…

Milder types include ‘Beaver Dam’, a really large podding type, which is quick to grow and can be stuffed or used in a salad. For a slightly warmer flavour, you might prefer purple jalapeño, which is also an attractive plant.

Germination is key

You need a propagator for germination, at a minimum of 22°C, or ideally 28°C. If you sow seeds in the ideal conditions, they can germinate in six to 10 days. Cooler temperatures will result in much slower germination times.

“Don’t sow too early. Some people sow in January or February, but you’d be wasting your time. Sow chillies in early March through to late March. They will grow faster because the light’s better,” Parker advises. “If they need watering, use warm water, not water straight from the tap which will be too cold and you’ll stop the germination. Then the seed will have to heat up again. Use water that’s the same temperature.”

Potting them on

If growing chillies in a pot, you can put six to eight seeds in a 9cm pot in a standard seed and potting compost. If you’re using a propagator, take the lid off as soon as the seeds have germinated because lids reduce light levels, even if they are clear plastic or glass. Too little light will make seedlings leggy.

Don’t overwater them, and transplant when there are two mature leaves big enough to handle on each seedling and pot on to a 7cm or 9cm pot individually, using a good quality compost, and definitely not a soil-based one. You can put the plants outdoors from late-May onwards, after all risk of frost has passed.

Buy plants to save time

Small chilli plants can be obtained from garden centres, to be planted straight into a pot and placed in a sunny, sheltered spot on the patio. “If you put the plant close to a brick wall, the wall will act as a heat reservoir so you’re creating a little micro-climate to improve conditions,” says Parker.

Maintenance is key

Add granular slow-release fertiliser to the compost, which will feed your plants for three to six months, but also feed the plants with a high potash feed, such as tomato food, when the fruits have set.

Epsom salts (magnesium sulphate) and seaweed extract (calcium nitrate) can also be watered in. Do that from time to time from flowering onwards. “Epsom salts improves the quality of the fruit, with better skin quality, and makes the plant look healthier, while calcium helps prevent deficiencies in the fruit.”

When will they be ready?

If you put your plants out at the end of May, you should be picking fast varieties by the middle of July onwards.

“’Super chilli’, for instance, is very quick and you’d be picking green pods in mid-July and red pods at the end of July and beginning of August. Flavours do change depending on the ripeness,” says Parker. “Purple jalapeño is nearly black to start with and when it ripens it goes burgundy. With this one, you need to wait until it ripens. Others in their first stages, such as standard jalapeños, can be eaten green or red.”

Harvesting and preserving

“Once you’ve picked them, chillies will keep in a fridge for several weeks. You can keep them longer by freezing them. I just freeze them whole and they do retain their heat,” adds Parker. “They may go a bit mushy, like soft fruit, but if you are using them in curries and stir-fries it doesn’t matter.”