The Chilli Cave

In the UK chillies are usually grown as annual plants and discarded at the end of each season. However, in their native habitats they are perennials and over the course of years can grow to the size of small trees. With careful nurturing, chillies can make it through the unpredictable UK winters and into the next spring.

The advantage is that the plants will be fully developed in plenty of time for flowering and fruiting and therefore have a longer season and, hopefully, be more productive.

This is particularly useful for the slower-growing superhot varieties such as Habaneros, Nagas and Scorpions, some of which are only hitting their peak just before the first frosts arrive.

In order to prepare the plant for overwintering you need to put the plant into a dormant state.  This can be achieved by cutting back the majority of the growth, just leaving 6 inches or so of main and a few side stems. Cut back on the feeding and watering and leave in a sunny spot with a temperature of around 10-15 degrees centigrade. 

There are more than a few people out there who can offer far better advice than I can so I'll let them do the talking;

Clifton Chilli Club has a great video here.

And chilli-master Matt Simpson offers his sage advice here.

Before I was able to overwinter my most valuable plants, I needed somewhere to store them.  Without enough windowsill space, I had to resort to artificial lights.  I've got a couple of 125W CFL (Compact Fluorescent Lamp) units which although not bright enough to grow a plant throughout the season, are certainly capable of overwintering one.  If I could find a suitably frost-free spot then I would be ready for the winter.

The garden shed was the perfect size but was a little damp and draughty so I would need to seal and insulate before I could install the necessary benches and lights. Thus began the most over-engineered project I've ever undertaken in the name of hot sauce...

Floor is sealed with membrane paint and the underlay is added.

Laminate flooring going down. 

The floor is finished.

New rafters for the ceiling and the first of the plywood panels go up.

The existing light is above the new ceiling so a fluorescent fitting is added to the ceiling.

Meanwhile, battens are screwed to the outside walls, and MDF panels are fixed over Rockwool insulation. 

Cramming insulation into all the gaps that might let in a draught.

The end wall is completed.

Plenty of insulation is added into the ceiling space and last panels screwed into place.

Side wall panelled and yet more insulation going in. 

Finished boxing in the window.  This will have a reflective blind over to keep the light in at night. 

One coat of white paint over everything. Another to follow.

Reflective film is added to the walls.  The diamond pattern on this material helps scatter the light, preventing 'hotspots'.

The blind is added over the window. This can be easily removed in the spring when the room can revert to being a tool shed.

Benches were made from some spare worktops and some scrap 2x4 lumber.  To test their strength I jumped up and down on them - if they can cope with me then the chillies will be a breeze.

The grow lights were then attached to chains, fixed to the ceiling with cup hooks.  This is a quick & easy way of altering their heights to adjust to the growth of the plants.  because CFL lamps don't produce much heat, the bulbs can be placed very close to plants if needs be.

The finished room.  The shelving in the middle will hold the propagators with some additional fluorescent strip lights.

 So the room ready to use.  I need to check the temperatures with a maximum/minimum thermometer to determine how much heating is needed, if any. Humidity may be an issue when the plants start growing in spring but by then it may be mild enough to allow an air vent or fan to be fitted without fear of freezing the plants.

Next step - relocating the chillies...