Feeling the cold? Turn up the heat and grow chillies!

Published on January 27th 2019
The urge to sow something, anything, to get the new garden season going, is an itch a lot of us really struggle with. It really is too early. We can provide heat to get seeds to germinate but natural light levels just aren't enough.
But chillies are an exception, the fruit needs a long time to ripen and the UK's growing season isn't long enough. Sowing indoors from January will provide you with strong, well-grown plants ready to transplant as soon as the last frost has been, normally in May.
I know from conversations on the plot, lots of my neighbours have already got theirs started.


Chillies and peppers are all cultivars of Capsicum annum which is why you'll see them classed together at shows. Here in the UK, we separate them into "chillies" meaning the hot spicy ones and "peppers" to refer to the sweet, mild and bell peppers, however, modern breeders have confused the matter by developing sweet jalapenos and hot bell peppers.
Once you've worked out your tolerance on the Scoville scale, there are lots of varieties and cultivars to pick from and it's worth growing several to provide a summer-long supply. These are just a few on our database.


As you'll be growing indoors, it's worthwhile using a sterilized seed compost to avoid bringing in any fungal diseases which could "damp off" new seedlings.
  • Sow the seeds on the surface and gently cover with a fine sprinkling of the compost of vermiculite.
  • Ensure the soil is moist by placing the tray/pots in tepid water for 10 mins then remove and allow to drain.
  • Cover with polythene and place in a warm airing cupboard or heated propagator at 18 to 25°C (64-77F)


Germination should occur within 7 to 10 days and at that point you can move the seedlings to a heated greenhouse or a warm sunny windowsill.
If you have grow lights, the seedlings will benefit from being under them for 18 hours a day for the first week dropping down to 12 to 16 hours after that. This will help prevent them from getting leggy.
For those of us growing on a window sill, remember to turn the pots a little every day so the seedlings don't lean towards the light. Keeping the glass clean also increases the amount of light.
If you've got no space on your windowsills to propagate seeds, garden centres, plant fairs and village shows will often have young plants for sale.

Pricking out and potting on

When the seedlings are big enough to handle, it's time to transplant them into individual 7.5cm (3") pots. Only touch the leaves and use a dibber to gently tease the roots out. When replanting bury the stem up to the leaves as this helps prevent them getting leggy.
It's worth feeding these young plants but only once a week with a low strength mix maybe 5:5:5 (N:P:K)
When roots appear through the pots drainage holes, pot the plants on again into 13cm (5") pots. Then finally into 2-litre pots.

Outdoor preparation

On warm sunny days, it's also worthwhile popping the young plants out for 15 minutes at a time to start hardening them off ready to be planted out. The length of time can be increased on cloudy days, there are no structured guidelines to hardening off as it is weather dependent.
When your plants are ready you can either plant them into the ground about 50cm apart or if your growing space is limited they can be planted into grow bags, 3 plants to a bag.
The beauty of chillies is that they can be grown in or outdoors, in greenhouses, conservatories and polytunnels, in the ground or in containers making them a plant that almost anyone can grow.

Tips to ensure a bumper crop.

  • Pinch out the tops of the plants when they get to 20cm tall as this will make them branch out getting thicker and more self-supporting.
  • Provide support by staking the young plants when they get to 30cm (12").
  • Water sparingly but regularly, especially in hot weather as this will intensify the fruit's flavour.
  • Once flowers have appeared, feed every two weeks with a balanced liquid fertilizer.
  • If you're growing indoors open windows to allow pollinating insects to do their thing or use a paintbrush to transfer pollen from flower to flower.


Early sown chillies can be ready to be harvested from August onwards, but if you still have fruit that hasn't ripened by the time summer is over, cut the whole plant and hang it upside down in a sunny windowsill. They'll continue to ripen provide they haven't been hit by frost.
Having written this, I'm off to get my box of seeds out, the need to sow is strong but space is limited, so what varieties? Please share your recommendations with the hashtag #chilli. Not Mike Smith's 'Dragon's Breath' (2.48million on the Scoville Scale) Wales can keep that one!

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