When to sow parsley

Outdoors, sow parsley once the soil is no longer frozen and has started to warm, usually from April. Under fleece you can start in March. Sowings can continue into July, and in mild areas into late summer for leaves that carry on into winter and the following spring.

For an early crop, sow indoors or under glass from February or March in small pots or modules, a few seeds per cell, and plant the young plants out later without splitting the rootball.

Temperature makes a big difference to how long you wait. At 68°F parsley can be up in about 12 days; at 54°F it takes around 25 days, and in cold soil at 41°F six weeks or more. That slow, uneven start is normal and the most common reason people think their parsley has failed.

Parsley grows in sun or light shade and wants fertile, humus-rich soil that stays moist but never waterlogged. Loosen compacted ground before sowing.

Sow thinly in drills 0.4–0.8 in deep and 8–12 in apart, cover and keep the soil evenly moist the whole time until the seedlings appear. If the drill dries out in those weeks, the seed often fails.

Once the seedlings are big enough to handle, thin them to about 4–6 in. Flat-leaved varieties grow larger and can have a little more room.

In a pot, choose one at least 10 in wide and deep with peat-free compost, keep it watered and give a liquid feed every few weeks.

Keep the soil moist in dry spells. Plants in the ground rarely need feeding if the bed was well prepared.

Start picking once the plants have a good rosette of leaves. Take the outer, older stalks and cut them near the base; the plant keeps producing new leaves from the centre. For a big batch you can cut the whole plant back to just above the ground and let it regrow.

Parsley is a biennial. It survives moderate frost and often keeps a few leaves through winter, though hard frost without snow cover can kill it. A cloche or fleece keeps leaves coming in cold weather.

In its second spring the plant gives leaves for a few more weeks, then runs up to flower in early summer and the leaves become sparse and tough. Most gardeners sow fresh every year and pull the old plants once they bolt.

Flat-leaved parsley has the stronger flavour and grows into bigger plants. Curly parsley is milder, more decorative, and easy to tell apart from poisonous look-alikes (see below).

Root parsley is the same species grown for its pale, parsnip-like root, which tastes of celery and parsley. It is sown in early spring like parsnips, needs wider rows and a long season, and the roots are lifted in late autumn.

Parsley is often said to be "incompatible with itself": sown where parsley or other carrot-family crops grew recently, it tends to grow poorly or die off. The practical rule is simple: give it a new spot every year, and keep it well away from recent carrots, parsnips and celery.

Pests include aphids (on leaves and on roots), slugs and snails, carrot fly and celery leaf miner.

Fool's parsley (Aethusa cynapium) is a poisonous weed of gardens and fields and looks very like young flat-leaved parsley. Its leaves smell unpleasant when crushed. Only harvest from plants you sowed yourself, and weed the rows carefully; this is one reason many gardeners grow curly parsley.

Parsley is often planted with tomatoes or among carrots, and some UK advice says its scent masks carrots from carrot fly. We found no good evidence for that, and parsley is itself a carrot-fly host, so don't rely on it. Treat pairings as tradition.

The rule with a real reason: keep parsley away from other carrot-family crops, and from the spot where parsley grew last year.