How to grow herbs from seed on your windowsill

Just follow these top tips from our green-fingered correspondent

Coriander seedlings will grow more quickly if you keep the pot in a greenhouse or on a windowsill (Rex Features)

Mint, sage, parsley, thyme and marjoram are the herbs traditionally used in English cookery. The herbs I use most are basil and coriander – neither of them British natives. The Romans, who used coriander to preserve meat, brought it to us with their conquering armies, and fortunately, though it was used to warmer climates than ours, coriander decided it could grow here, too.

You can sow it now in a pot, though it will grow more quickly if you keep the pot in a greenhouse or on a windowsill. At a temperature of around 18C/65F, seed should germinate within five to 10 days. I used to grow coriander from seed bought at a health food shop. It was some while before I realised that there are two quite distinct strains: one produces lots of leaf, the other shoots straight up into seed. Both are useful, but I always want more leaf than seed and the health-food-shop coriander was not that kind.

If you, too, want leaf, look for 'Calypso' (Thompson & Morgan £1.99), 'Cilantro' (Chiltern £1.70), 'Slow Bolt' (Chiltern £1.75) or 'Leisure' (Chiltern £1.70), all of which have been specially bred to go on producing new leaf after cropping, like a cut-and-come-again salad crop. The advantage of British-bred 'Calypso', which I've grown for the past couple of years, is that the leaves break very low down on the stem, so you can cut at least three times before the plant gives up trying to replace what it has lost.

Because it has carrot-like roots, coriander does not transplant well. The shock makes it bolt. So you need to sow seed in a pot large enough to contain the plants for the whole of their lives. I generally use pots 28cm/11in across, because I want plenty to cut. You certainly shouldn't use a pot smaller than 13cm/5in. Fill the pot with compost, firm it down lightly and water it. Sow the seeds thinly (they are big enough to sow one by one) and cover them with perlite or vermiculite. Stick in a label marked with the date of sowing.

Because it's an annual, coriander is programmed to complete all it needs to do within one single season. So, at some stage, even the specially-bred leafy kinds will get tired of growing and leap up into seed. Therefore, for a continuous crop, you need to sow fresh seed at monthly intervals. That's why you need the label and the date of sowing. Without the prompt, you'll never remember it.

Water your pots regularly, but only when the compost has begun to dry out. Coriander doesn't like to be too wet, but like most edible greenstuffs, it needs to grow fast. Scissor off the young leaves as you need them. The first leaves are like flat French parsley, but as the plant shoots up, the leaves become much more wispy and have a different taste.

If you are sowing in succession, you can chuck the first sowings, when the supply of leaves begins to run out. Unless, of course, you want to gather seeds, too. They are generally ready to harvest by August. You need to be quick to catch them. They drop as soon as they are ripe. By April it should be warm enough to sow direct outside, if you want to. For late supplies, sow outside in August and September, then under cover in October.

Both chervil and dill can be grown in the same way as coriander. Sow a batch of chervil this month, under cover, then make direct sowings outside in August and September. Sow seed of dill in batches between May and August, either in a gutter to slide into place outside, once seeds have germinated, or directly into the soil. Unlike coriander, chervil and dill do not change leaves as they grow, so it is not quite so vital to catch them at the right time. Both can be treated as annuals, though chervil is actually biennial.

Fresh chervil is a revelation to anyone used only to the dried stuff. It has ferny leaves and hollow stems – white flowers, too, if it is allowed to grow on for a second year. Like all natural biennials, when it has flowered, it dies. It grows quickly and you can pick useful quantities of leaves only six weeks after sowing seed. You have to get fresh seed each year. It quickly loses its potency. Sown outside, chervil does better in light shade. Sow the seed thinly in pots or a deep windowbox.

Chervil is hardy, so you can expect the last sowings to stand through the beginning of winter reasonably well, though growth will come to a standstill. With a greenhouse, you can keep a fresh supply of leaves going all through the winter. Take out flowering stems as they appear, to encourage the plant to leaf up again. Once it has produced seed, it thinks it has done its job and starts to die back.

Dill, like coriander, can be used either for its leaves or its seeds. It looks like fennel, but is smaller in all of its parts, the plants reaching about 100cm/36in. It has thread-like leaves and flat heads of yellow flowers from June to August. Chiltern, who list an exceptionally good selection of herb seeds, offer five different kinds. They suggest 'Bouquet' (£1.70) as the best for dill seed, and vigorous 'Dukat' (£1.80) for a thick crop of blue-green foliage. Their best seller is 'Tetra' (£1.85), bushy, vigorous and slow to bolt.

These three herbs are so easy to grow from seed, this is the strategy I'd recommend. But perhaps you think it all seems too much bother. Perhaps you'd find it difficult to cart home the necessary compost. Perhaps you've nowhere on your overcrowded windowsill to keep the seedlings as they are growing. In which case, you can order young plants from Delfland's organically-grown range. Five plants of coriander will cost £1.95, five of chervil the same amount. But their plants won't be ready to send until May.

Thompson & Morgan, 0844 573 1818, thompson-morgan.com; Chiltern Seeds, 01491 824675, chilternseeds.co.uk; Delfland Nurseries Ltd, 01354 740553, organicplants.co.uk