Heaven scent: Gardening in the Guyanan rain forest

The easiest herbs to grow are the permanent ones: rosemary, thyme, sage, tarragon. You buy a plant, stick it in the ground and away it goes.

To these you could add winter savory (Satureja montana) which, like tarragon, is perennial. In a mild season it stays in leaf all winter. If it doesn't cooperate, grow it in a pot and bring it under cover. Then you can be sure of a constant supply of leaf to use in bean stews. It's a compact plant, no more than 30cm tall, 20cm wide and in summer has a crop of lippy pink or white flowers. In my last garden, I used it as an informal edging in one part of the herb patch. It's not as neat as dwarf box, but more productive. Like many Mediterranean herbs, it does best in poorish ground and needs plenty of sun. If you've never tasted it, think thyme or marjoram. It has the same kind of tang.

A more unexpected perennial herb, in this country at least, is lemon grass. I potted up some I bought in a supermarket and to my surprise, it grew. It's not hardy of course, so when the nights began to get chilly, I put it in the cold frame. There, it still gets plenty of light, but can be kept free of frost. The top growth died down, but new shoots pushed out in spring and kept us in fresh leaf all summer. At the moment, the pot is back in the cold frame, but I'm hoping it will resurrect itself again when the days begin to get longer.

India is its home, but I first came across it in Guyana, where it grew in vast clumps like pampas grass underneath the canopy of the rain forest. At that time, my husband and I were making regular expeditions into the most inaccessible areas of Guyana with a small group called Remote Area Medical, set up by my Guyanese sister-in-law. She's a doctor and her idea was to try to bring help to some of the most scattered Amerindian communities – Macushi, Waipashana and Wai-Wai – living in the rain forest. We'd only go where we were invited and we'd only do things that didn't get in the way of their own very successful medicine. But a course of antibiotics can stop a child dying from a septic piranha bite. And, in a culture where the bow and arrow is paramount, a pair of glasses means that a hunter can continue to feed his family.

So with guides provided by the head man of each small community, we walked from village to village through trackless, mapless rain forest. As well as medical supplies, we carried all our own food, so we wouldn't be a burden to any group we stayed with. One time, on a three-week walk, our basic supplies (cassava, rice, beans) began to run out. All we had left was sugar. For four days, we lived on sugar and boiled water, flavoured with the leaves of lemon grass. On particularly tough sections of the trail, even that began to seem as desirable a treat as a four-course dinner at the Ivy.

So I'm rather attached to lemon grass, and a few leaves chopped up in a glass with honey and hot water remains my favourite drink. You can chuck chopped leaves in a bath too, and get the same slightly oily, pungent smell around you as you wallow. That was a nicety we never got round to in the rain forest. Bathing there, in river pools and under waterfalls, you were more concerned about cayman and piranhas than you were about aromatherapy. Lemon grass is said to be a good antidepressant, but that wasn't a concept familiar to the Macushi. They used it to ease stomach aches and fevers.

It may have been beginner's luck, the fact that the stems I bought rooted so easily. But if you look at the faintly bulbous sticks packed in their transparent bags, you can sometimes see slight swellings or bumps at the base of the stalks. These are the growing points from which roots and shoots may come. But as with a daffodil bulb, if the cut has been made too far up the swollen base, there's no hope that it will be able to make roots and grow.

You can also stick the stems in a glass of water and hope they will root in the way, for instance, that mint will. It may be four or five weeks before you see these developing. When you do, lift out the stems and pot them up. Don't be tempted to use too big a pot. In our cool climate, the plants are prone to rot and too much damp compost sitting around the roots only increases the danger. You can try growing lemon grass from seed too, but germination is slow and erratic, even if you manage to maintain a temperature of 20-30C, which is what the seed requires. Potting up stalks is much easier.

If you're using lemon grass in a stir fry or to make Thai fish cakes, you need the bulbous bottom end of the plant, rather than the leaves. With a sharp knife, it's easy enough to wiggle a stem free from the clump and cut it right down at the base. But you can't do this too often. The rate of growth in our climate isn't as vigorous as it is in the tropics.

Once the plant is established in a pot, there is very little you have to do except cut down the top growth when it dies down in winter. During this dormant period, lemon grass needs very little water. When the plant starts into growth again, begin to water and feed it using a liquid fertiliser high in nitrogen, which will boost leaf growth.

You don't need a garden to keep yourself in lemon grass. Or winter savory. A sunny windowsill can be the Mediterranean and the tropics all in one.

For all you need to know about growing herbs, get hold of the new revised edition of 'Jekka McVicar's Complete Herb Book' (Kyle Cathie, £25) – she's a guide you can trust