Cumin

The herb most British gardeners try once, struggle with, and abandon — and that is a fair reaction, because cumin is genuinely difficult here. It comes from the hot dry plains of Egypt, Iran and India, and expects long warm summers, low humidity and relentless sun. Our weather offers none of those reliably.

Grow it under glass or not at all. Outdoors in Britain the plant will usually grow and flower but the seed rarely ripens before the autumn cool arrives, leaving you with green heads and no spice. A greenhouse, polytunnel or sunny conservatory gives it the warmth and dryness it needs to finish.

Be honest with yourself about the yield: a few small jars rather than a year's supply. But freshly harvested and toasted, the flavour is a long way from a supermarket jar, and there is real satisfaction in having managed it at all. The plant itself is pretty too — lacy foliage and small white umbels, in the same family as parsley and dill.