Time to Sow Chilli Seeds

It’s a great time of year to get your chilli seeds sown and Mark Hodgson, a passionate chilli grower, who runs Langholm Chilli Club, let’s us in on everything you need to know to get started.

It seems unlikely in Scotland, but it is perfectly possible to grow fantastic chilli plants here. All you need is a warm windowsill, some seed compost, and a dose of T.L.C.

Chilli plants were exported from South America in 1492. Due to their ease of growing, and obvious use in cuisine, there are now tens of thousands of different varieties worldwide; ranging from Bonsai plants that grow to about the size of a football, up to six foot monsters with fruit about the size of a small football. 

The chilli fruit, and in some cases the foliage, comes in every colour of the rainbow and ranges in heat from sweet peppers to the current, hot, world record holder: the Capsicum chinense ‘Carolina Reaper’. 

Sweet peppers have no heat at all, whereas the ‘Carolina Reaper’ comes in at around 220 thousand Scoville Heat Units (SHU). Scoville Units is the index used to identify the heat in a chilli fruit. To put this in context, the jalapeno you get on a frozen pizza is between 5 and 10 thousand SHU.

Despite expectations, chillies are incredibly easy to grow – even in Scotland – and can be grown in the space of about 10 months. Whilst in their native tropical climate, chillies are perennials that live for 20 years or more and grow to be tree size in height. The climate and daylight hours in Scotland usually mean people grow them as annuals, sowing in January or February, or even earlier for some of the hotter varieties, and harvesting the fruit from August onwards. 

There is no great secret, except perhaps germinating the seeds in the first place. After that, they are tough cookies and probably more straightforward than a lot of common house or greenhouse plants.

Starting Out

Pick your chilli varieties carefully. Check how quick, colourful, hot, and above all how big the variety you wish to grow is – if you only have one bathroom windowsill to grow them on, you do not want a 6 foot giant by August. 

Get your seeds from a reliable source, either a fellow grower or a specialist supplier. 

Ideally sow in January, or earlier for some varieties, but it is not too late to get sowing now if you are quick. As a rule of thumb, the hotter the fruit, the longer you need to get to harvest. And some heirloom varieties, for example ‘Tabasco’ or ‘Mustard Habanero’, can take even longer. Put short, you cannot start early enough. 

Always sow more seeds than you could possibly need. Germination rates are usually around 75 per cent but, with good germination, you will have some spares to give out to friends to make them smile and to start your own chilli club. 

Sowing the Seeds

Any kind of finely textured compost is fine, generic seed compost is perfectly adequate. 

The seeds need a minimum constant 20C/ 68F to reliably germinate. So if you do not have a heated propagator or heat mat, make space in your airing cupboard.

Pop the seeds into moist compost, cover with soil very lightly, not more than the briefest covering, cover with a lid or clingfilm, and keep them warm.

Germination times are between seven days and a month – the hotter they are, they slower they go.

Growing On

As soon as the seedlings are up, they will need some light, although not a great deal: warmest windowsill during the day, and then pop them down by a radiator at night, or back in the airing cupboard. At this point, heat is more important than light. 

There is no need to add additional feed, as long as the compost was fresh, it will contain more than enough nutrients. 

When the seedlings reach the 6-8 leaf stage – usually within 4 weeks of appearing – transfer them into 3 inch pots, with fresh compost. Seedlings are very delicate so be gentle!

Vegetative Stage (March – June)

From March to June is where it gets awesome. The chillis will grow and grow and grow. In larger varieties, like ‘Cayenne’ or ‘Pimiento’, you can practically measure the height gain on a daily basis. 

Use a general purpose feed every two weeks, like Miracle-gro or an organic equivalent, not a tomato feed yet!

When the plants are taller than the pots they are in, re-pot them. Moving them, for example, from 3 to 6 to 12 inch pots – three transfers is more than enough. 

As ever, warmth is key. Do not take them into the greenhouse unless it is heated until the last frosts have absolutely passed. If the temperature gets below 3C, it’s game over.

There is no recommended frequency of watering, it depends on the environment. Compost should be damp but not wet, like a wrung-out sponge. The best test is to poke a finger into the soil: it should feel damp but no compost should stick to the finger. Watch for signs of wilting, and watch for overwatering, chillis can handle drying out for short periods better than they can being waterlogged.

There is no need to trim or prune, they are not tomatoes. Medium and large plants, though, really need a cane to prop them up when the fruit starts arriving. Be careful not to damage the roots when you are putting the cane in the compost (2 canes stuck in the edge of the pot, angled in, and tied to the plant stem like a ‘tepee’ avoids this).

Grow lights or heat mats can help speed up the process, but they are not necessary. Do not get too hung up on technology, it’s way more fun to grow them naturally.


Chilli flowers are amazing. Small, usually between 2 and 5cm across, but amazing. They first come out in the later stage of vegetative growth. They can be everything from pure white to deep purple, and some have a variegated corolla, particularly those in theBaccatum’ family.  

Early flowers have a tendency to shrink and drop off, stalks and all, and this always distresses first-time growers. Do not worry, it is just the plant trying to work out why it is in Scotland and not in the Ecuadorian Jungle.

Within two to three weeks from the first buds opening, you should start checking inside the flowers to look for a little green ‘bobble’ – that is your first ever proto-chilli. 

Once flowering begins, overall plant growth will start to slow down, and once a few fruits have appeared, stop altogether.


As soon as you see your first ‘bobbles’, switch from general purpose feed to tomato feed, or an equivalent high potassium nutrient, to encourage fruit development and prevent the plant wasting energy on further vegetative growth. Usually, some of the early fruits, and their stalks, will die and drop off when they are tiny.

Chillies will self-pollinate and begin fruiting automatically, usually in late June or early July. The rest of the fruit will develop over 2-3 months.

You will always get one fruit – usually the lowest one on the plant – which develops more quickly than any others. It hurts, but take it off the plant. Again, this is just the chilli plant being confused about which continent it is on.

Ripening and Eating

Despite what every celebrity chef on the planet seems to think – green and red chillis are not separate things! It is just unripe fruit versus ripe fruit. Most fruits, except purple or firework varieties, start off green then ripen to their final colour. Unripe fruit has a different taste to ripe ones: less heat, less sweetness, but with a sharper taste. Ornamental varieties in their unripe stage can be purple, black, or random multicolours – they will all change colour sooner or later.

Fruits usually take 4-6 weeks to reach their full size and shape. As a guideline, picking some of the underripe chillis in the first couple of months of fruiting will encourage more fruit to develop, giving about a third extra yield over the lifetime of the plant. Later fruits will change more quickly and from September onwards, will start to ripen immediately, even as they are growing.

After fruits have ripened, they have another couple of weeks before they start over-ripening. Watch for softening, dark or black spots, or wrinkling. If you see any of these, it is best to crop that fruit and pop it in the fridge.

Plants will keep trying to flower and fruit well into October, but fruit will not really get any bigger after the end of September. In a warm house, chilli plants can keep going well into December.


Overwintering chilli plants is your decision. The plant will drop all or most of its leaves. After that, it’s a 50/50 chance on whether or not it will bounce back next year, dripping with fruit or remain an embarrassing stick. It is up to you but it is far more fun to start all over again next January.

Mark says, “Langholm Chilli Club was started as a joke in 2017, just a bunch of locals looking for something to do over the winter months. The Club currently has 1400 members across the world – from Kenya to the Falkland Islands, and still has a sense of humour. Langholm Chilli Club members recorded growing 189 different varieties of chillies last year. There are no rules to joining the Club except that you plant too many chillies and give them out to other people to make them happy.”

You can join Langholm Chilli Club on their Facebook Group.

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