Chillies are relatively easy to grow their primary requirement being warmth, particularly at the early stages. Chillies originate from the tropics, which is why they need warm conditions.
Chillies are ideal to grow in containers, and unless you want to eat Chillies every day, a couple of plants will keep you well supplied. Chillies like sun and warmth and in sheltered gardens, especially in the south of the country, Chillies will crop outside but elsewhere they are best grown under glass. Early in the year it will be too cold in an unheated greenhouse or poly tunnel for seeds or a young plant Chillies are best kept indoors until the later in the summer and definitely do not plant out until the risk of frost has passed.
Whether you grow from seed or buy a Chilli plant as soon as it starts flowering is a signal to being weekly feeding. Recommended is a feed high in potash such as tomato feed, which is ideal. Also, when the plant comes into flower, pinch out those early flowers so that the Chilli plant will throw out more shoots, bush and produce a better crop.
Chillies are best grown in a dry sheltered spot, and if grown in containers, keep on the dry side. Towards the end of the season you can bring the Chilli plants back inside to keep them growing and fruiting. If you are growing Chillies indoors, you will need to open windows or doors to allow the pollinating insects in.
If the leaves of the Chilli plant turn yellow, or drop off, the likely cause is over-watering. The general rule is to water Chillies sparingly.
There is a gardening debate about whether you can over winter chilli plants. It is true to say, especially in northern climates, Chillies are best treated as an annual. Even if you persuade the Chilli plant through the winter, the ensuing plant will be less vigorous, if not feeble, and you may not get much by way of fruit.
Equally, for the cost of a chilli plant you can compost it and buy another each year they are still great value cropping from one small chilli plant maybe 40+ chillies
The RHS undertook a trial of chillies for those most to look for those most suitable to grow in containers, suggestions are: 'Riot' a long thin chilli, moderately hot; 'Krakatoa' a thicker cone shaped red chilli hot; 'Spike' a thin, very hot chilli. These are all short compact chillies suitable for container growing in a warm spot bearing in mind chillies are H1 hardy which is 5-10 degrees.
Chillies are ideal for growing in containers, on windowsills and balconies, and make a great veg plant where space is limited. There is a range of vegetables which can be grown in containers, for more information about growing vegetables in containers.