CHILLI plants hail from warmer parts of South America. As a result, they aren’t natural candidates for growing in temperate countries like the UK, unless you have a greenhouse. But they also do well in pots, so if you have a suitable spot by a window to nurture them indoors, you can produce a good crop of chilli peppers.
The chilli is such a valuable culinary addition because it contains a chemical called capsaicin that binds to heat receptors called TRPV1 on our tongues, triggering sensations ranging from tingling to agony, depending on the concentration. The discoverer of this process won a share of the 2021 Nobel prize for physiology or medicine.
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The reason for such chemical warfare is unclear. One idea is that it deters munching of the fruit by mammals. Leaving them available to be eaten by birds – which have a slightly different form of the heat receptors and so are impervious to their effects – allows the seeds to be spread further. But capsaicin might also help the plants by blocking the growth of a fungus . Either way, some of us humans relish the kick chillies bring to food.
To grow your own, germinate some seeds in late winter or early spring in a heated propagator or on a sunny windowsill in pots covered with plastic bags, to create a miniature greenhouse.
As the seedlings grow, they no longer need a cover and can be moved to progressively larger pots. In warmer parts of the UK, you might get away with putting the plants outside in sunny weather, once they are a good size, although this may reduce the crop.
The flowers should be self-pollinating, but to be safe, gently shake them to help the pollen reach the stigma in the centre. Once the fruits form, some growers advocate a range of strategies to get hotter chillies, including tearing off a few leaves to mimic munching by herbivores – this is supposed to make the plants produce more capsaicin in defence. Or just buy varieties that are naturally hotter, such as Prairie Fire – there is a huge range.
This year, I will be trying something new: keeping a chilli plant alive over winter. In contrast to the plant’s summer needs, you are now aiming for a cool-enough temperature range, of 5°C to 12°C. Depending on the weather, this could be somewhere such as a shed, garage or a front porch.
Before overwintering, harvest any remaining fruit, then cut off all branches and trim the top off the main stem so you are left with just 15 centimetres. For convenience, place in a smaller pot, trimming the root ball if necessary, and store. Water only when the compost is getting dry.
In late winter or early spring, awaken the plant by moving it to a warm and sunny spot. This will give you a head start on a good crop of fruit the next summer.
What you need
A packet of chilli seeds
A propagator or a small plant pot and plastic bag
Larger pots
A cane for support
A sunny spot indoors or a greenhouse
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