Growing chillies in the UK is entirely achievable, even in our cooler, shorter summers. The key to success is starting seeds early indoors in January or February with a heated propagator, keeping seedlings warm and well-lit through the darker months, then getting plants into a greenhouse or outside once the threat of frost passes in May. Most varieties will reward you with a good harvest from July through to October, with slower varieties like habanero and naga benefiting from the extra warmth of a greenhouse or conservatory.
We have been growing chillies in the UK since 2006 and this guide covers everything you need to know. From choosing and germinating seeds right through to harvesting and overwintering your best plants for a head start next season we will share our 20+ years of growing experience.
When to Start Growing Chillies?
Exactly when you plant your chilli seeds will depend on your available growing space and conditions. Below i’ll talk about what I do here in the UK.
If you have the space it is best to plant your seeds early in the year (Jan/Feb) and nurture the seedlings indoors or under glass. This will give you a good head start on the growing season. Your plants can then be put outside (or even better in a greenhouse) once the threat of frosts pass. This will enable you to maximise your harvests later in the year.
Germinating Chilli Seeds
Chillies can be germinated much as any other seed. In order to give the seeds a bit of a helping hand to germinate you can place the seed in between two sheets of damp kitchen roll and put into a either a sealed freezer bag or plastic container. Place the bag somewhere warm such as in an airing cupboard or on top of a refrigerator. This method will help keep the heat and the moisture around the seeds, speeding up the germination process.
After 2-5 days you will probably notice some of the seeds will have swelled up and may be even be starting to sprout. Now is the time to plant the seeds. Ideally you need a heated propagator however if you can keep the seeds in your house where the temperature is warmer and more constant temperature then a regular seed tray should do. My preference is to use small seed modules as they make it very easy to transplant and pot the seedling on later.
Of course you can take the easier approach and simply plant your chilli pepper seeds straight into the compost. Remember that different varieties take different times to germinate. If you are growing habanero peppers for example you can expect them to take up to 3 or 4 weeks to germinate, whereas annum varieties such as cayenne will sprout much quicker.
When planting chilli seeds aim to space them about 5cms apart in normal multi purpose compost, ideally mixed with some vermiculite. Then lightly cover the seeds with about 0.5cm of compost and water them with a fine rose or spray. Check them every day and spray with a little water if they look a bit dry. The aim is to prevent the compost from drying out rather than keeping it wet.
The two main requirements that the seed has at this stage are heat and moisture. The optimum temperature for germination varies from species to species but roughly speaking can be said to be in the region of 23-30 degrees Celsius (about 73-86 Fahrenheit). To learn more read our guide to the best germination temperatures.
A heated propagator is the single most useful piece of equipment for UK chilli growers to make germination rates high – see our guide to the best options at every budget.
To improve the germination rate of your chilli seeds try and keep the temperature of the seeds constant. The best way to do this is to use a heated propagator. If you don’t own one, anywhere in the home with constant low level heat source will do, for example on top of the refrigerator. Here is my favourite way of speeding up germination.
The time taken for germination varies greatly between varieties. More common varieties such as Apache or jalapeno usually germinate in anything between 1-3 weeks. Other more fickle varieties such as Habenero may take up to 6 weeks or longer. The key is to be patient!
Related: Our detailed guide to germinating chilli seeds.
Post Germination
Once your seedlings have poked their heads out of the compost they suddenly have a new requirement for you to fulfill, light. This can be where growing in a northern climate such as the UK can present more of a challenge.
If growing in your house, place your seedlings on a south facing windowsill or conservatory. If temperature allows, a greenhouse is one step better however ensure that night time temperatures are >10 degrees Celcius.
If your chilli seedlings look tall and thin and lean towards the light then they are what we call ‘leggy’. In order to fix this you have to main options:
Firstly you will need to give the plants more natural light (see below). Secondly (and only when you seedlings have turned into young plants) you can consider pinching them out to encourage bushier growth. For advice on pinching out to encourage bushier growth, see our guide to pinching out chilli plants.
Growing Chillies Under Grow Lights
One of the most effective things a UK grower can do to improve plant quality and extend the growing season is to use artificial lighting. The difference between seedlings raised under proper grow lights and those struggling on a January windowsill is immediately visible: compact, sturdy plants versus tall, leggy ones that have been reaching desperately toward a grey winter sky.
You don’t need a complicated or expensive setup to make a real difference. Here’s a brief overview of your main options:
LED grow lights are now our first recommendation for most growers. Modern full-spectrum LED panels run cool, use a fraction of the electricity of older lighting types, and produce excellent results from seedling stage right through to flowering. A mid-range panel such as the VIPARSPECTRA P1000 or Spider Farmer SF600 costs less than £100 and will last for years. Position the panel 20-60cm above your seedlings and run it for 14-16 hours per day using a simple smart plug as a timer.
Fluorescent tubes are the cheapest starting point if your budget is limited. They still work perfectly well for the earliest seedling stage. A couple of cool white fluorescent strip lights mounted above a seed tray — total cost under £20 — will significantly outperform a dark windowsill in January and February. The limitation is that fluorescent tubes don’t have the spectrum or intensity to take plants much beyond the early seedling stage, so plan to move to natural light or LED as plants develop. Check out my simple light box setup to see how these can work.
The key rule regardless of light type: position lights close enough to be effective (most people keep them too far away), run them for 14-16 hours per day on a timer, and give plants a minimum of 6-8 hours of darkness — continuous light is not beneficial and wastes electricity.
If your seedlings look tall and thin despite being under lights, either the light is too far away, the daily hours are insufficient, or your panel isn’t powerful enough for the number of plants you’re trying to illuminate. Move it closer, extend the hours, or consider whether you need a more powerful panel.
For a comprehensive guide to choosing the right grow light for your setup — including specific LED recommendations at every budget from under £35 to £185+, how many hours to run them, and how to use them alongside natural light — see our complete guide to grow lights for chilli plants.
Growing Chillies Indoors or on a Windowsill
Not everyone has the luxury of a greenhouse or a south-facing garden. The good news is that chillies are one of the most rewarding vegetables you can grow entirely indoors. A warm, south-facing windowsill is sufficient to produce a meaningful harvest of the right varieties, and a kitchen windowsill covered in pods of ripening chillies in August is a genuinely beautiful sight.
Choose the right variety and indoor growing becomes significantly easier. Aim for compact upright varieties specifically bred for small container or windowsill growing as these perform dramatically better indoors than sprawling greenhouse varieties. Our top recommendations for windowsill growing:
Apache F1: A reliable compact plant producing clusters of upright red pods. One of the most consistently productive windowsill varieties available. Readily available from most UK seed suppliers.
Demon Red: Very small plant with tiny upright pods that ripen through green, black and vivid red. Ornamental enough to double as a houseplant, productive enough to keep you in fresh chillies through summer. This is our favourite variety to grow in our kitchen! See our full Demon Red growing guide for more detail.
Prairie Fire: Extremely compact with tiny fiery pods. Maximum ornamental impact on a windowsill with genuine heat.
Cayenne: Grows larger than the above but produces prolifically on a south-facing windowsill or conservatory given enough light. May need a small cane for support as it develops. Prune the plant early to encourage bushier compact growth.
Avoid growing habanero, naga or scotch bonnet varieties on a windowsill as they need more heat and light than most UK windows provide and the results are typically disappointing compared to growing the same varieties in a greenhouse.
Light is the limiting factor indoors. A south-facing windowsill receives the most direct light and is strongly preferred. East or west-facing windows may work for compact varieties but expect slower growth and fewer pods. North-facing windows don’t receive enough direct light for reliable fruiting. If this is your only option, a grow light is the practical solution rather than trying to push plants beyond what the available light will support.
The windowsill temperature matters as much as the light. Chilli plants sitting on a windowsill directly above a radiator benefit from warmth during the day but can experience cold draughts at night when the radiator goes off and the window glass chills the air immediately in front of it. If your windowsill plants show signs of cold stress (drooping or yellowing leaves in the morning despite adequate watering) try moving them back slightly from the glass overnight during cold snaps.
Grow lights transform windowsill growing for the early season. From January through to April when UK daylight hours are short and light intensity low, even a south-facing windowsill struggles to provide enough light for compact, sturdy seedling development. A small LED grow light positioned above windowsill plants for 14-16 hours per day eliminates this problem entirely and produces noticeably stronger seedlings than natural light alone in the dark winter months. See our complete grow lights guide for specific recommendations at every budget.
Potting On Your Chili Plants/ Out
Once the seedlings have developed their second set of leaves it is time to re-pot them. I usually opt for pots about 10cm in diameter. Be very careful not to damage the seedlings during the potting on process. One good tip is to avoid touching them altogether by re-potting the area of compost around the seedlings roots. By doing this hopefully you will avoid damaging the roots of the plant.
What type of pot you use is pretty unimportant. You can save money and use old yogurt pots or recycled plastic drinking cups while the plants are still small. Of more importance at this stage is to decide what potting medium to use.
Depending on the time of year, your location and amount of light available, you can keep the plants on your windowsill, in the greenhouse or under artificial lighting. Pepper plants love light, so the more they get the faster and stronger they will grow. If space is an issue inside then I can highly recommend one of the many mini greenhouses available. You can pick these up for only a few pounds and while they may not last forever they will certainly protect you chilli plants in early spring.
Depending on the variety you will most likely need to re-pot the chillies on again in a few weeks time. It is a good idea to avoid potting on your plants too early. Doing so can focus the plant’s growth on growing the roots rather than stems, leaves and flowers. A general rule of thumb is to only increase pot size when roots are appearing through the drainage holes at the bottom of the pot.
Once the risk of frost passes you can put the plants outside. Initially you might want to harden them off by placing outside for just a few hours a day. This will get the plants used to the direct sunlight and winds gradually.
During these early stages of growth your plants can be particularly susceptible to pests like aphids. Take a look at our pests and diseases article for ways to keep your young plants healthy.
Growing Chillies in Pots and Containers
Most UK chilli growers grow in containers rather than in the ground. Pots give you complete control over the growing medium, and importantly allow you to move plants to warmer positions as the weather dictates. Pots also make overwintering your chilli plants much more practical at the end of the season.
Almost all chilli varieties grow well in containers, from compact windowsill varieties like Apache and Demon Red through to larger spreading plants like Rocoto and habanero.
Choosing the right pot size matters more than most growers realise. Based on our own pot size experiment (running the same variety in different sized containers over a full season) most varieties perform best in a final pot of 7-10 litres (roughly a 10-12 inch pot). Counterintuitively, very large pots don’t always produce the best results. Plants that are slightly root-bound tend to flower earlier and more prolifically than those with unlimited root space. The mild stress of restricted roots triggers the plant’s reproductive response. Going bigger than 12 litres rarely improves yield and often reduces it unless you are using a very well heated greenhouse.
What compost to use is another important decision. Standard garden soil is not suitable for container growing as it compacts in pots, drains poorly and frequently introduces disease. Use a good quality peat-free multi-purpose compost mixed with approximately 20% perlite for improved drainage and aeration. Adding a small proportion of very well-rotted manure to the final pot can provide a slow-release nutrient base. See our full guide to the best potting medium for chilli plants for our exact recipe and ratios.
Watering container-grown plants requires more consistent attention than growing in the ground. Pots can dry out quickly during hot spells (a plant in a 10-litre pot in a greenhouse may need watering daily during July and August). The reliable test: push your finger an inch into the compost, and water when it feels dry at that depth. Don’t rely on a schedule, rely on the compost. See our complete guide to watering chilli plants for more on technique and seasonal adjustments.
Feeding container plants consistently is more important than for ground-grown plants because nutrients wash out with each watering over the course of the season. We use liquid tomato feed at half the recommended strength applied weekly from first flowering through to late summer. A specialist chilli feed such as Chilli Focus gives excellent results and is specifically formulated for the nutrient requirements of chilli plants at each growth stage.
What to feed chilli plants
One of the most asked questions is how often to feed pepper plants and what with? In the early growth stages I just water them as required. Ideally this is with harvested rainwater if not tap water is fine. How often to water depends on the heat. Typically in Spring this is once a day increasing to possibly twice a day in summer.
Once the plants start to flower I introduce a few drops of liquid tomato food into their water during every other watering. I use half the dilution strength recommended for tomato plants. Doing so gives the plants the extra energy required to keep producing fruit over the summer months.
When it comes to watering, base don our readers comments we have found overwatering tends to be the main problem. For more information take a look at our comprehensive guide to watering chilli plants.
For our complete guide to what to feed, when to start and how much to use see our complete chilli plant feeding guide
Chilli Plant Flowers and Fruit
As your pepper plants begin to mature you will start to notice flowers appearing on your plants. This is the sign you have been waiting for as it means that your first chillies are not that far off. All that stands between you and fresh chilli pods is pollination.
Be aware that different varieties of pepper flower and fruit at over various different time periods. Varieties such as Cayene and Jalapeno grow earlier and quicker than varieties such as habanero, scotch bonnet or naga. Slower varieties require more heat and light and are best kept in a conservatory or greenhouse to ensure the optimum harvest.
Pollination will be taken care of naturally by bees and other insects if you plants are grown outside. If you are growing inside your plants may suffer from flower drop. If this is the case you might want to consider hand pollinating your plants. Don’t worry, this is not as sordid as it may sound. To do so lightly rub your little finger inside the flower heads on your plants. Alternatively use a small artists paint brush or a cotton bud. This will do the bees job of moving pollen around from flower to flower.
Eventually you will see that some of the flowers will go brown and drop off. This is usually no need for alarm as the cause will be a chilli pushing its way through the flower. All you need to do now is to keep up the water/food and wait for your chillies to ripen.
End of Season – What to Do with Your Chilli Plants
As Autumn arrives and UK temperatures begin to fall, it is time to think about what to do with your plants before the first frosts arrive.
Harvest everything you can. Before temperatures drop significantly, pick all the chillies on your plants — ripe and unripe. Unripe green chillies are perfectly usable in cooking, and any remaining fruit can be ripened off the plant on a warm windowsill. Don’t leave pods on the plant once temperatures regularly fall below 12°C as the fruit quality deteriorates. See our guide to knowing when chillies are ripe for how to assess each variety.
Preserve your harvest. A late summer glut is the perfect prompt to try some of our most popular preservation recipes. Our chilli chutney and chilli jelly both use large quantities of fresh chillies and keep for up to a year. For something quicker, our chilli oil recipe takes under 20 minutes. Surplus chillies can also be dried for homemade chilli flakes or frozen whole for use through winter.
Consider overwintering your best plants. Most people don’t realise it but chilli plants are perennials in their native climate. In other words they don’t have to die at the end of the season. Overwintered plants come back in spring weeks ahead of any seed-grown plant and often produce a significantly larger crop in their second and third years. The process is simpler than most growers expect: prune back heavily, repot into fresh compost, keep frost-free and water sparingly until spring growth appears.
Our complete guide to overwintering chilli plants covers the full process including whether to prune hard or leave plants to shed naturally, how to keep plants through the winter without specialist equipment, and what to expect when plants break dormancy in spring.