How to grow Chillies

Chillies Growing Guide

If you thought a packet of red, green and yellow chillies from the shops, both undersized and overpriced, was as exciting as the fiery fruits got, think again, growing chillies in the UK is much easier than you might think. In fact, the most interesting ones are only available to home growers – from chunky and fleshy to blunt-ended and potently hot, growing chilli plants is a must for any spice lover.

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Chillies quick links

How to grow Chillies

Although more than 3,500 varieties of chilli are estimated to exist, one of the hottest in the world is grown not in the tropics, but right here in the UK. The ‘Dorset Naga’ was bred from the Bangladeshi ‘Naga Morich’ on a smallholding in southern England. In fact nearly all varieties of this member of the tomato and potato family can do very well in this country.

Most chillies grown in the UK are usually produced as annual greenhouse plants, although some varieties will crop well if grown indoors in pots on a warm kitchen windowsill or, at the other end of the scale, outdoors on the veg patch.

Chilli plants can reach anywhere from 25–180cm in height and produce glossy, mid-green leaves, as well as masses of star-shaped, whitegreen flowers in late spring to late summer which go on to form the small, edible fruits. In the kitchen, the peppers provide a spicy twist to meat and vegetable dishes, such as chilli con carne and guacamole.

They vary tremendously in their shape and colour (there are red, yellow, green, orange and purple forms) and also in the amount of ‘heat’ they contain. For this reason they should always be treated with care, as some chilli varieties are intensely hot and can easily make your mouth and throat burn when eaten.

Preparing the ground for growing chillies outdoors

If you’re planning to grow your chilli plants outside, you will find they establish themselves more quickly if you cover your proposed planting site with cloches a few weeks beforehand to warm-up the ground before planting.

For the best results, always select a sheltered, sunny spot with a well-drained but moisture-retentive and reasonably fertile soil for growing your chilli plants in. When planting, fork over and mix a trowelful of multipurpose compost into the base of each planting hole and backfill around each rootball with a mixture of excavated earth and further compost.

Growing chillies from seed

Chillies require a long cropping season in order for fruits to ripen and develop their heat, so chilli seeds are best sown from January to March for greenhouse and indoor cultivation, and in April for outdoor cultivation.

Fill a seed tray to just below the rim with moist John Innes seed compost, firm it in to create a level surface and then scatter the chilli seeds thinly on top. Finally, cover the seeds with a 5mm layer of compost or vermiculite and place the tray in a heated propagator at a temperature of 21–25°C.

If you only want a few plants, you can sow chillies into small pots rather than a tray. Once the seedlings emerge (germination usually takes 10–21 days) and have two obvious leaves, prick them out individually into 7.5cm diameter pots filled with John Innes no.1 compost – try not to disturb the roots too much and always handle each seedling by a leaf, not the thin stem, to lower the risk of damaging the young chilli plant. Afterwards, position the chilli seedlings in a warm and well-lit greenhouse or conservatory.

If you don’t have a heated propagator, after you sow the seeds, place the tray or pot in a warm airing cupboard instead to get faster results. However, it’s essential to cover your chosen container with a clear plastic propagating lid or cling film and to check the compost on a regular basis to make sure it doesn’t dry out. As soon as the seedlings appear, the tray must be moved to a warm and well-lit greenhouse or conservatory. Chilli plants should then be pricked-out in the same manner as those raised in a heated propagator, when they have two obvious leaves.

Chilli plant final growing stages

When the seedlings have developed five pairs of leaves or are around 15cm in height, they should be transferred to their final growing positions.

For greenhouse varieties, plant the chillies individually into 20–25cm diameter containers filled with John Innes no. 2 compost, or place two plants at either end of a grow bag. Certain varieties are happy to be raised on a warm kitchen windowsill such as ‘Apache’ and ‘Red Missile’, and these also need to be grown in pots. If you have a mild plot and want to grow chillies outside, then harden off the plants for two weeks at the end of May or early June, by placing them out on the patio or in a cold frame during the day and bringing them back under cover at night – this will allow the plants to adapt to the change in temperature. When planting, space the chillies 60cm apart in rows that are at 90cm intervals.

Alternatively, plant them in suitable pots, harden them off and then leave outside on a warm and sunny patio.

Greenhouse-grown chilli plants prefer a minimum night temperature of 12–15°C and a maximum day temperature of 30°C – this can be maintained by heating the structure (when necessary), opening the ventilators and damping-down the floor on hot days.

Do chilli plants grow back every year?


Most chillies are forms of Capsicum annuum and, as such, are annual plants and should be discarded (composted) when they stop producing fruits in the autumn rather than holding onto them in the hope they’ll grow back next year.

However, a few chillies, notably the species Capsicum baccatum and Capsicum pubescens (which include the varieties ‘Lemon Drop’ and ‘Rocoto Red’ respectively) are short-lived perennials and the plants can be overwintered indoors and used to raise fruits the following summer as plants will grow back. Once they have finished cropping, pinch out the growing tips and cut back all the side shoots to 5cm in length, before placing each pot on a greenhouse ‘heat mat’ at a temperature of 12–15°C.

During the winter, ensure the compost is kept just moist and feed the overwintering chilli plants at every watering with a one-quarter strength high-potash liquid fertiliser – this will help to keep their immune systems healthy, giving them some defence against winter fungal diseases. When the chilli plants sprout again, re-pot them and revert to a high nitrogen feed to induce lots of fresh, new growth. Overwintering chillies indoors can be a handy way to get a headstart on the season and grow chilli plants faster in your second season.

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Growing Chillies month-by-month


Chillies are one of the earliest crops to get started, so whether you’re growing yours indoors, in your greenhouse or out on the plot, you’ll want to decide which varieties you’d like this year, and order them now.


If you haven’t done so yet, order chilli seeds from a specialist supplier. For greenhouse growing, sow the seeds and leave to germinate in a heated propagator in order to help them on their way, this will lead to faster germination. Transfer young seedlings into small pots.


Continue with sowing under cover where young chilli seedlings will be protected from the cold conditions outdoors. For faster growing results from the start, a heated propagator is advisable to get chillies under way.


For outdoor growing, sow the seeds under cover and ideally leave them to germinate in a heated propagator. Alternatively, cover the same trays and pots with cling film and place in a warm airing cupboard. Transfer the young seedlings from a March sowing into small pots. Plant the chillies from a January or February sowing in their final growing quarters. In warm spells, ventilate and damp down the greenhouse. Aim to keep the chilli plants uniformly moist.


Transfer the young seedlings from an April sowing into small pots. Plant the chillies from a March sowing in their final growing quarters. In warm spells, ventilate and damp down the greenhouse to keep heat levels in check. Do it first thing in the morning, so the water evaporates during the day. Keep the chilli plants moist and apply a liquid feed. Towards the end of the month harden-off April-sown chillies before planting them outside.


In warm spells, ventilate and damp down the greenhouse. Keep the chilli plants uniformly moist and apply a liquid feed. Harden off April-sown chillies before planting them outside. Be ready to protect outdoor chillies with fleece or cloches in adverse weather conditions.


When the weather warms, ventilate and damp down the greenhouse. Keep the chilli plants uniformly moist and apply a liquid feed. For plants that have been ripening for the longest, and depending on your conditions, the first chillies should be ready to harvest and store this month.

Must do this month!

During the summer heat it’s important to ventilate and damp down the greenhouse. Apply liquid feed to plants and keep the soil moist. Continue to harvest and store the chilli fruits.


Harvest and store the fruits in order to have enough to keep your winter meals packed with flavour and heat.


Use up chilli harvests in a tasty and warming chilli con carne, or a vegetarian chilli recipe, a hearty chilli dish at this time of the year will be a real crowd-pleaser. Across the cold months, if you’re overwintering chilli plants that’ll grow back next year, keep soil moist and well-fed.


Make the most of your harvests and if you grew too many chilli plants that you can use yourself, consider turning some into fiery chilli jam or chilli pickle to give to a friend or relative at Christmas.


Chilli growing kits make a great festive gift for the gardener or foodie in your life, these ready-to-grow packs are usually one of the easiest ways for beginners to get started and contain everything needed for growing chillies from seed.

Caring for your Chillies plants + problems

During the main growing season, the compost and garden soil needs to be kept uniformly moist at all times but waterlogging must be avoided. Greenhouse plants also require regular misting with tepid water to create a humid atmosphere, especially when they are flowering, as this will stimulate ‘fruit set’ and help prevent attacks by the sap-sucking pest, red spider mite.

A method of support is usually required for the main stem of taller varieties and a stout cane is ideal for this purpose – always cover the top of each one with an old cork to prevent accidental eye injuries. When the first flowers appear, liquid feed the chilli plants using a high-potash fertiliser on a weekly basis. If a spell of unseasonally cold weather is forecast, always cover outdoor specimens with a protective sheet of horticultural fleece or cloches. And, if any of them get too tall (indoors or out), they can be kept in check by simply pinching out the growing tips back to healthy leaves.

How to harvest Chillies

The chillies should be left to ripen on the plants and are harvested when they are firm, crisp and fully coloured. They should be picked regularly when they are ripe, as this clears the way for new ones to form. Once collected, chilli fruits can be used fresh (eaten raw or cooked), dried and frozen.

Varieties of Chillies

Chillies varieties to try

Jalapeño Chilli

One of the most widely-used and easiest chillies to grow, the jalapeño is highly popular in many chilli recipes due to its medium spice rating that most people can handle. Delicious in salsas or pickled.

‘Bhut Jolokia Fiery Furnace

Also known as the ghost chilli, this is the hottest chilli in the world scoring over a million on the ‘Scoville scale’, so it’s not for the faint-hearted. Sow early to allow it to ripen to a vibrant red; grows well in pots indoors or under the protection of a greenhouse.

'Ají Limon'

Bushy chilli plant producing high yields of lemon yellow chilli peppers with a zesty citrus zing, the ‘Ají Limon’ is slow to germinate but once it does it’s a prolific cropper and well worth the wait.

‘Numex Twilight’

Eye-catching and colourful, the ‘Numex Twilight’ chilli turns from purple to yellow to orange and finally red as it ripes, so it’s a really special chilli plant. Produces an abundance of medium-hot fruits and makes great patio crop if grown in a container, where a greenhouse isn’t available.

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