When to plant strawberries

Strawberries are perennials: you plant them once and pick from the same plants for a few years. The best time to plant is from mid-July to September. The earlier they go in, the more roots and crowns they build before winter, and the better the crop the following June. In Germany, Austria and Switzerland, mid-July to mid-August is ideal; in the UK, August and September are the classic months.

Spring planting, from about March to April, also works. Summer-fruiting varieties planted in spring give only a small first crop, because they haven't had time to establish. Everbearing varieties catch up faster and fruit the same summer.

Plants usually come as potted plants, bare-root runners or cold-stored runners (frigo plants). Cold-stored runners planted in late spring fruit about two months later, which is a handy way to get a crop in the first year.

Choose a sunny spot with fertile, free-draining soil that is slightly acidic to neutral. On heavy or wet ground, a raised bed is the safer choice, because strawberries rot in waterlogged soil. Work in compost before planting, around 5 litres per square metre.

Depth matters more than anything else. Set each plant so that the base of the crown, where the leaves emerge, sits right at the soil surface. Plant too deep and the crown rots; too shallow and the roots dry out. German gardeners say the heart should see the sky. Firm the soil and water well.

Space plants 12–16 in apart in rows 24–31 in apart. In a 120 × 80 cm raised bed, two rows of four plants at about 12 in × 16 in give you 8 plants; packed into three rows you can fit 12, but the plants then stay damp longer and grey mould finds it easier.

Water newly planted strawberries regularly until they are established; after that, only in long dry spells. Water the soil, not the plants: wet fruit and crowns invite grey mould.

Once the flowers fade and the first fruits form, tuck straw under the plants. It keeps the berries clean and dry. Clear it away after harvest or in autumn so it doesn't harbour slugs and fungal spores.

Feed lightly. A high-potassium organic fertiliser in spring is enough on reasonable soil; too much nitrogen gives lots of leaves and soft, mould-prone fruit.

Plants send out runners from early summer. Unless you want new plants, cut them off so the plant's energy goes into the crop. To raise your own, peg a few strong runners into small pots in late summer and cut them free once they have rooted.

Frost can kill open flowers, leaving a black centre. If a frost is forecast during flowering, cover the plants overnight with fleece.

Summer-fruiting strawberries crop heavily for about three to four weeks, usually in June and into July depending on variety. Pick often, as soon as the berries are red all over, and clear out any mouldy ones as you go.

A bed doesn't last for ever. Yields and fruit size fall off after the second or third crop, and diseases and viruses build up. Plan to replant after two to four years, in a new spot, using healthy certified plants or rooted runners from your best plants.

An easy way to keep strawberries going: plant a new bed every year or two and dig up the oldest one, so you always have plants in their best years.

Summer-fruiting (June-bearing) varieties give the biggest berries in one concentrated flush of a few weeks. They are the choice for jam and for a proper glut. Early varieties such as 'Honeoye' and late ones such as 'Symphony' or 'Senga Sengana' spread the season if you grow both.

Everbearing (perpetual) varieties, such as 'Ostara' or 'Mara des Bois', crop in smaller flushes from early summer until autumn, with smaller fruit. They suit containers and anyone who wants a few berries at a time.

Alpine strawberries are a different species, Fragaria vesca, with tiny, intensely aromatic fruit from late spring to autumn. They tolerate light shade and can be grown from seed.

Grey mould (Botrytis) is the most common problem: soft, grey, furry fruit, worst in wet weather and in crowded beds. Space plants well, keep water off fruit and crowns, pick often and remove rotten berries straight away.

Slugs, snails and birds love ripe berries; net the bed before the fruit colours. Vine weevil grubs eat the roots, particularly in containers. Leaf spot diseases, powdery mildew and root rots can also appear, the root rots mainly on wet, heavy soil.

Strawberries are in the rose family. They don't need a vegetable rotation slot, but they do suffer from replant problems: soil-borne fungi and nematodes build up under them. Put a new bed where strawberries haven't grown for at least four years, ideally five to six.

Garlic, onions, leeks and borage are the classic strawberry companions in planting tables, often with claims about grey mould or slugs. We found no solid evidence for these; they are tradition. Planting a few alliums in between does no harm.

More useful: keep strawberries away from ground that has just grown strawberries, and give them enough space and air.