Carrot

Light and exposure

The carrot wants sun, at least six hours a day, to form fine, sweet roots. An open, sunny position is ideal from spring to autumn.

It tolerates light shade in high summer, which is not much of an issue in a cool temperate climate but becomes a real asset wherever summer stays above 25 degrees. What matters above all is soil that does not obstruct the root and good light for vigorous foliage.

Watering

Regular watering is decisive, especially during germination and while the roots are forming. The soil should stay cool without ever being waterlogged. During germination, which is slow, do not let the surface crust and dry out, or the young seedlings cannot break through.

After that, consistency is key. Swings between drought and heavy watering make the roots burst and split. A prolonged lack of water makes them fibrous and tough. A light mulch, once the plants are well up, helps keep the moisture steady.

Soil and repotting

This is the critical point of the crop. The carrot requires deep, loose, fine soil free of stones. In heavy, stony or freshly manured soil, the roots fork, deform or stay stunted. Never add fresh manure before a carrot crop.

In heavy soil, as is found in a great many gardens, work the soil deeply, remove the stones and lighten it with well-rotted compost and a little sand. If your soil stays difficult, choose short or round varieties, or grow in a deep container filled with a fine mix.

Temperature and humidity

The carrot is hardy and enjoys cool conditions. The seed germinates from 7 to 8 degrees, slowly, often in two to three weeks. The young plants tolerate cool weather and light frosts, and late-season cold even concentrates the sugars in the roots.

Direct sowing in open ground begins as soon as the soil has drained and warmed past that threshold, and continues into early summer, a little later still for a late-season harvest. Sowing too early in cold, wet soil is pointless, the seed rots or germinates very poorly. A forcing fleece warms the soil and brings forward the very first sowings.

Pruning and upkeep

The carrot is not pruned, but thinning is the operation that makes or breaks the harvest. Sown densely, it gives stunted, tangled roots. Thin in two stages, first to three centimetres when the plants have a few leaves, then to five or six centimetres a little later.

Thin preferably in the evening and in calm weather, then water, because the smell of the crushed foliage is precisely what attracts the carrot fly. Gather up and remove the pulled tops. During the season, a light earthing up of the crown stops it greening in the light and protects it from the first frosts.

Pests and diseases

The carrot fly, Psila rosae, is the number one pest in temperate climates. The fly lays at the crown, and its larvae tunnel brown galleries into the roots that make them inedible. The best defence is an insect-proof fleece laid at sowing and left in place, backed up by sowings that are not too early to avoid the first generation and discreet thinning in the evening.

Watch too for powdery mildew on the foliage in late summer, root rot in soil that is too wet, and slugs on the young plants. A crop rotation, not putting carrots in the same spot again for three or four years, limits the build-up of the fly in the soil.

Propagation

The carrot is always sown where it will grow, in open ground, because it does not tolerate transplanting, which deforms the root. Sow thinly in rows spaced twenty-five to thirty centimetres apart, barely one centimetre deep, in a well-refined furrow. Cover with fine soil or potting mix and water with a gentle spray.

Germination is slow, two to three weeks, and the surface must not dry out during that time. Mixing the fine seeds with a little sand helps to sow thinly and thin less afterwards. An old trick is to sow a few radishes in the same row, they come up fast and mark the line.

Month-by-month care calendar

Green Hub tips

• Lay an insect-proof fleece at sowing and leave it in place. It is the only truly reliable defence against the carrot fly.
• Thin in the evening, in calm weather, then water. The smell of crushed tops in broad daylight is what draws the fly to your rows.
• Work the soil deeply, without stones or fresh manure. In heavy soil, rather choose short or round varieties.
• Mix the seeds with sand to sow thinly, and slip a few radishes into the row: they come up fast and mark the line while the carrot germinates.