Curry leaves are an ingredient used in a range of Asian cuisines and yet in the West, there is a lot of misunderstanding about these plants. While these plants can be a great addition to a polytunnel, which will allow you to grow these tender plants in containers, it is important to understand how to identity these plants correctly and how and why they are used. First of all, curry leaves, as used in Asian cookery, are Murraya koenigii, not the same as the 'curry plant' Helichrysum italicum, which has a strong curry smell but is not edible. Secondly, curry leaves are not the same as curry powder. Curry leaves are used in Asian recipes in much the same way as bay leaves are used in other cuisines. They are used to add aromatics to a dish and picked out at the end – not eaten.
It can be a novelty to have your polytunnel filled with a strong curry smell and to be able to use this ingredient at home to prepare a range of authentic Asian dishes. Note, however, that in most of the UK, curry leaves will not be able to survive at our winter temperatures. Your polytunnel must therefore be heated in the winter, or you must be able to bring your plant inside when cold weather threatens.
Curry leaves are not the easiest plants to establish. They are commonly grown from seed but it can take 1-2 years for the plants to become established. Pinching and pruning while the plants are young is important as it will help to create a bushier plant that is good for harvesting. Removing the hard outer casing from the seeds will help them to germinate more quickly – always use fresh seeds.
Of course it is also possible to buy your curry leaf plants online or from some local plant nurseries. Do make sure that you get the correct plant, Murraya koenigii, and not Helichrysum italicum. It is easiest, whether your curry leaves are grown from seed or purchased, to grow them in containers, so these may be moved as you require.
Since the plants will usually be grown in containers, you must make sure that the plants get enough to eat. Fertilise your plants every five weeks or so with a good, organic fertiliser. When it comes to water, it is better to keep the plant on the dry side. Water only infrequently and let the soil dry out before watering again.
Simply pluck off the leaves as needed for use to add aroma to your Asian dishes. The more leaves that you take the bushier the plants should become.