In domestic gardens, chillies are most often grown as annuals. This makes a lot of sense in anything but the warmest of climates.

Although in the tropics many chilli varieties will happily grow as perennial evergreens, in any climate with a winter season, they'll usually die back in autumn. And if there's any significant level of frost, they'll more than likely not return.

However, with a little planning and effort, you can help your chilli plants survive the winter, and coax them into coming back year after year. This brings several advantages.

  • Overwintered chilli plants get a head start compared to slow-germinating seeds. This extends the growing season by several weeks, increasing the chances of a bumper, fully ripened harvest.
  • An extended season also widens the range of varieties you can grow. For example, some super-hot varieties require longer ripening times. Overwintering lets you squeeze every drop of sunshine from your summer months.
  • Overwintered chillies have already developed a healthy root system, and so can divert more of their energy toward fruiting. Typically, you can expect double the total yield in a plant's second year.

The Overwintering Method 

In the most northern parts of the country, you may be able to keep your chilli plants growing and fruiting year-round. However, in most regions, the shortening days and falling temperatures of autumn will start to send your plants into a dormant state.

It's easy to mistake this hibernation mode for a dying plant, but it's a normal part of the life cycle for chillies outside of tropical climates. The leaves will wilt and drop, and the stem will harden and dry. It's at this point you need to put your winter survival plans into action.

Chillies grown in containers or the open ground can both be overwintered. The technique is basically the same, but container-grown plants are the more likely to survive thanks to the greater level of protection you can provide.

Overwintering Chillies in Containers 

If you have several chilli plants, choose only the healthiest and most productive ones to overwinter. The process doesn't guarantee survival, so choosing healthy plants stacks the odds a little in your favour.

Also, accept that you're likely to lose a plant or two, so try to overwinter a couple more plants than you strictly need, to provide some insurance.

As autumn approaches, stop feeding your plants after the likely final flowering. Unlike animal hibernation, 'fattening up' your chillies before the winter is counterproductive, as it'll encourage your plants to sprout fresh foliage when their energy is better conserved for surviving the winter.

At this point, also start to reduce your watering. Combined with the shortening days, the dwindling feed and water supplies send signals that it's time to enter dormancy. The transition will usually start once overnight temperatures have fallen to 10C or so for a sustained period.

As the leaves start to fade, make sure you pick any remaining chillies, and pinch out any flowers which haven't yet set fruit. This helps conserve the plants' resources and diverts them to keeping the root system alive.

Next, cut the plant back ruthlessly, leaving only 10-15cm of the main stem. While this may seem drastic, it prevents the plant wasting its energy reserves on keeping foliage alive.

At this stage, you may like to remove the plant from its container, so that you can replant in a clean pot with fresh compost to give a nutritional kick-start in the spring. You could also downsize the containers for easier storage over winter.

However, be careful not to damage the roots, and be aware that the shock of transplanting can hamper regrowth, and even kill the plant when it's in its fragile dormant state.

The advantage of container chillies at this point is that they can be moved to a frost-free area, such as a greenhouse, outhouse, or even a cool room indoors. There's no need to keep them in direct sunlight, but neither should they be in darkness: your plants should be able to use the changes in daylight hours to sense when spring is on its way.

During winter, water the dormant plants extremely sparingly. Don't let the compost dry out completely, but overly moist soil risks mould or rot setting in. Check your containers every few days, and water only once the top 2-3cm of soil is bone dry.

As spring starts to near, you'll hopefully see new growth start to sprout. You can now step up your watering regimen a little, but still err on the dry side until there's enough foliage to evaporate any excess away.

Slowly increase your watering in line with foliage growth, moving your containers to a sunnier spot as the temperature allows. Once the first flower buds appear, begin feeding once again with a specific capsicum/chilli feed, or a more general tomato formulation.

Chillies Grown in Open Soil 

If you grow chillies in garden beds, you can still attempt to overwinter them, although the results are less certain.

The most reliable method is to dig the plants up, and pot them in temporary containers. You can then move them somewhere warmer, and proceed as for container-grown plants.

However, there are drawbacks to doing this. Transplanting is always stressful for mature plants, and the shock can weaken them to a greater or lesser extent. There's also the risk of damaging the roots, and as preserving a healthy root system is a major goal of overwintering, you could easily make the whole exercise pretty pointless.

But if your local climate is reliably frost-free, chilli plants can be overwintered in-place. The basic method is similar to that with containers.

  • Reduce watering and feeding as autumn approaches. 
  • Once the plant begins dying back, remove all remaining fruit and flowers.
  • Once the plant is well on the way to turning dormant, prune it back hard, leaving 10-15cm above ground. Do this well before any severe cold is expected to reduce the risks of damage or disease. However, don't do it too early, or you'll simply promote fresh growth, wasting precious resources.
  • Whereas containers can be moved to shelter, in the open soil a different kind of protection is needed. A thick organic mulch will help keep the soil warm, and if particularly harsh weather is forecast, wrapping the stems in fleece, fabric, or plastic is recommended.  

If the winter is kind, you should see signs of life returning in spring, and you can step up your watering and feeding routines once more.

Once you've caught the chilli-growing bug, it's great fun to experiment with new varieties from year to year - there's a huge range of interesting chillies to explore.

But starting from scratch every spring means you'll never get the most out of your most vigorous plants. Overwintering adds another dimension to your chilli-growing adventures, and while success isn't 100 percent guaranteed, it's less complicated than you might think.

Overwintering Chilly