Chilli plants are all perennial, meaning ‘unending or permanent’ and not annual or short lived. We are used to treating them as annuals because of our climate and associated winter temperatures. Nearly all chillies will be killed as a result of a period of frost. Plants that are successfully overwintered, could be productive for years to come.
What is overwintering
In simple terms, it’s keeping your plant alive throughout the cooler, darker Winter months. The simplest way, is to bring the plant inside and treat as a houseplant. However, we are taking things a bit further and making the most of any available space and keep as many plants alive, as required. We are looking to slow the plants growth down for a few months and let it semi-hibernate, conserving energy.
- The possibility of earlier fruit and longer fruiting period. This should mean more fruit.
- Fruit obtained will be identical to the previous seasons and not subject to unintentional cross breeding. Great for hard to find or special varieties.
- Fruiting may well be more productive the second and subsequent years.
- Saves time and money.
- Give the chilli obsessive grower something to do during the Winter.
When to overwinter
Overwintering is carried out at the end of the growing season, which is usually dictated by your areas first frost dates. In our part of the UK, it is towards the middle to the end of October. If you are not sure you can look up your projected first frost dates online, or keep an eye on the weather forecast.
Give yourself time, so you are not rushing and plan ahead. Give careful consideration to which plants will be overwintered, because suitable space is at a premium.
Plants will not survive, unprotected, in a greenhouse or poly tunnel . If that is your plan, you will need some form of heating or additional protection from the elements.
What you will need
- A healthy, pest free plant.
- Compost or other growing medium.
- Pots. Smaller pots allow more plants to be overwintered, in the same space.
- Somewhere warm, with no risk of frost and plenty of light, natural or otherwise. Plants don’t need to bask, they just need to survive. A south facing window will do fine, although don’t let the plant touch the glass.
The availability of space may mean you have to consider a heated grow mat and or grow lights. Remember we are keeping them alive, not growing them on, at this stage.
How to overwinter
- Prune branches and stems. Stems can be pruned down to about 10-15 cm from the surface of the compost. Prune to just above a node. Remember you can use the pruned sections for taking cuttings and increase your stock further.
- Trim roots. If you are re-potting the plant in a smaller pot, trimming the roots is essential. Simply expose the required amount of roots and trim with sharp, clean scissors.
- Remove all fruits, ripe or otherwise. If a fruit has started to ripen, it will continue to do so off the plant. Removing fruit allows the plant to conserve energy.
- Reduce watering. Keep the compost on the dry side of moist. Use the weight of the pot as an indication of the moisture. Watering roughly every other week should be fine.
- Plants close to de-humidifiers, radiators or forced air central heating will need more watering.
Not all your plants will survive the overwintering process. Sometimes there is no rhyme or reason as to what succeeds and what dies. Of the five domesticated species, some have a higher success rate than others, but with practice, all can be successful.
Annuum varieties seem to have the highest failure rate, whilst pubescens and baccatums have the highest. Annuum are quicker to grow from seed, so all is not lost.
For several weeks after being pruned and repotted, plants can almost look dead. If branches suffer die back and turn brown, prune the back to green wood. Eventually, new growth will emerge from nodes and form new branches and leaves. The speed at which this happens, depends on the available light and warmth.
When you water, take a moment to inspect to pests. Check the undersides of leaves and the surface of the compost. Deal as appropriate. See the Pests Section.
If you have suffered with pests, prior to overwintering, remove as much of the compost as possible and run the entire plant under a garden hose, to rinse off unwanted visitors. Use fresh compost and keep a close eye on the plants. Consider preventative measures, like applications of Neem oil.
As the hours of available daylight and the intensity of that light both reduce, it is normal for plants you are overwintering to drop leaves. Don’t panic, it’s a survival mechanism. You may well end up with a leafless stem. All is not lost.
In Spring, around mid May, re-introduce your plants to the outside world, after the risk of frost has gone. Pot them on, into bigger pots and start a general, light feeding regime. Start watering more often and as required.