Key points for healthy plants
Keep them warm and pest–free
1 Plants in pots are more vulnerable to extreme cold than those in the ground. As well as insulating inside your pot, throw fleece over the plants on very cold nights, removing it as the temperature rises to allow trapped condensation to dry out.
2 Pests are a problem whatever the time of year, so protect your plants as you create your pot. I use copper tape against slugs and snails getting in – it is said deter them by giving them an electric shock as they crawl across it.