Home Gardening techniques How to overwinter chillies

How to overwinter chillies

Chilli Razzamatazz - one to be overwintered
Chilli Razzamatazz in August 2019

Get a head start next year by saving your favourite plants…

Most people throw chilli plants away at the end of the season but they’re perennials and with a bit of care will come through the winter to perform even better next year.

ROOTIT Heat Mat – Large from Amazon

Only attempt to keep potted plants from one year to the next (most people do anyway). If they’re grown in a greenhouse bed, the root disturbance and damage of being potted up will lessen their chances of survival.

I’m keeping four varieties (I’ve included the heat in Scoville Units, the measurement of heat in chillies) For more on this and growing chillies from seed, visit my page here:

  • Biquino Red (very mild, sweet, tiny Brazilian, 50 SHU)
  • Razzamatazz (multi-coloured, prolific, medium heat, 5,000-20,000 SHU)
  • Trinidad Moruga Scorpion (second-hottest chilli in the world, 1,200,000-2,000,000 SHU). I’m not daft enough to eat it, it’s for my stepson!
  • An unnamed long red mild variety which was a gift and has previously been overwintered.

For more on growing super hot chillies, check out my post here.

Unnamed mild red chilli
Unnamed mild red chilli

Why try to overwinter plants?

There are several advantages:

  • Next year’s harvest will be earlier, produce more fruits and over a longer period. This is useful for varieties such as naga or habanero that can have a very short fruiting season when young
  • They’ll have established rootballs and will burst back into life producing new leaves when the days lengthen
  • You’ll save money buying seeds
  • Overwintered plants will have a massive head start over seeds sown in late winter/early spring
  • Some are easier than others – Habaneros and Cayenne overwinter easily, while Jalapenos are a challenge.
Chilli Pepper (Hot) Biquino Red. Picture; Johnsons
Chilli Pepper (Hot) Biquino Red. Picture; Johnsons

When to start overwintering

When the temperature drops below 10°C at night under glass (about the end of October) plants start to shut down for the winter. Growth virtually stops, reducing light and water needs drastically.

Pick off all the ripe chillies, as this sends a signal to the plant that it will need to produce more fruit next season.

Chillies back from left, Razzamatazz, unnamed, Biquino Red; front Trinidad Moruga Scorpion before pruning
Chillies back from left, Razzamatazz, unnamed, Biquino Red; front Trinidad Moruga Scorpion before pruning

Heat and light levels

Plants must be overwintered in an environment warm enough for humans – a south-facing window is ideal. Don’t let plants tough the glass or trap them behind curtains on cold nights.

Light levels are much better in a conservatory but the temperature is lower than the house, so my plants are sitting on a heat mat set to 10°C. It’s thermostatically controlled, so only comes on when it needs to.

Chillies back from left, Razzamatazz, unnamed, Biquino Red; front Trinidad Moruga Scorpion after pruning
Chillies back from left, Razzamatazz, unnamed, Biquino Red; front Trinidad Moruga Scorpion after pruning

Pruning and potting

Plants also need to be pruned, although there’s some debate as to by how much. Some experts say cut back stems by 10-15cm, others just to cut back any dying branches to where the wood is green, and yet more say prune plants right back, leaving a short stem to concentrate the plant’s energy. Take your pick!

Some people recommend repotting plants in slightly smaller containers but mine are staying put, as this seems to contradict the root damage advice given above.

Watering and feeding

At this time, the plant will virtually stop growing, reducing light and water needs drastically, while preparing for winter. The need for fertiliser also stops.

Only keep the compost barely moist – check weekly but they may only need watering once every 2-3 weeks. Watch out for any mould growth.

Use a moisture tester if you’re unsure – keep soil at about 25 per cent moisture.

Aphid colony
Aphid colony

Possible problems to watch out for

Aphids: They make a beeline for chillies, especially in winter, so check plants regularly. If you find any, wash or spray with organic pest killer.

Dropping leaves: A natural response to the low temperatures and light levels of the winter.

NEHS chilli plant contestants
NEHS chilli plant contestants at Harrogate Autumn Show

Starting plants back into growth

In March, when there are equal hours of daylight and darkness, repot plants in a multipurpose, peat-free, compost. Remove any loose old compost from around the rootball. Using the same pot or a slightly bigger one, pot it up and water in well.

As warmth and light increases, the plants will start to grow and produce new leaves. Increase watering and after a month, start fertilising again.

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Mandy Watson is a freelance journalist and an incurable plantaholic. MandyCanUDigIt grew from the tiny seed of a Twitter account into the rainforest of information you see before you. Gardening columnist for the Sunderland Echo, Shields Gazette and Hartlepool Mail and editor of the Teesdale Mercury Magazine. Attracted by anything rebellious, exotic and nerdy, even after all these years. Passionate about northern England and gardens everywhere. Falls over a lot.


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