Carrots are grown by sowing seed directly where they are to grow — their long taproot resents being transplanted, so module-raising and moving them usually produces forked, stunted roots. Get the soil and sowing right and the rest is mostly patience and protection from carrot fly.
Soil comes first
Carrots need deep, loose, stone-free soil. Stones, lumps and fresh manure cause roots to fork and split, so grow them in ground that was manured for a previous crop, or in deep containers or raised beds of sieved, low-fertility mix. Rich, freshly fed soil grows leaves and forked roots rather than clean carrots.
Sowing direct
Sow thinly, about 1 cm deep, in drills once the soil has warmed in spring, and continue with successional sowings for a long season. Because the seed is tiny, mixing it with sand or sowing pelleted seed helps you sow thinly and cut down on thinning later. Keep the soil evenly moist until germination, which is slow — often two to three weeks.
Thinning — and the carrot-fly trap
Thin seedlings to about 5–7 cm apart so roots can swell. Here is the catch: the smell released by thinning and crushing carrot foliage attracts carrot fly, whose larvae tunnel into the roots. Thin in the evening, in still weather, remove all thinnings, and firm and water the row afterwards to reduce the scent. Sowing thinly to minimise thinning is the best defence of all.
Protecting from carrot fly
Carrot fly is the crop’s main enemy. The most reliable protection is a physical barrier: cover the crop with insect-proof mesh or fleece, or grow within a tall (60 cm+) barrier, since the low-flying females struggle to get over it.
Common problems
Forking and splitting → stony ground, fresh manure, or irregular watering after drought. Green shoulders → tops exposed to light; draw a little soil over them. Poor, patchy germination → soil dried out during the long germination period. Carrot fly → tunnels and rusty tunnelling in the roots.
Harvesting
Pull carrots as you need them once they reach usable size; earlies are sweet and tender, while maincrops can be left in the ground and lifted through autumn. Ease them out with a fork in heavy soil to avoid snapping the root. For reliable germination see seed germination.
Types of carrot
Carrots range from quick, slender early types (such as Nantes and Amsterdam) for spring and summer pulling, to sturdier maincrop types (such as Autumn King and Berlicum) for autumn lifting and storage. Short, round or stump-rooted varieties are the answer for shallow, stony or heavy soils and for container growing, where long-rooted types would fork.
Growing carrots in containers
A deep pot, tub or trough of sieved, low-fertility mix is an excellent way to grow clean carrots and to keep them off the ground and away from carrot fly. Choose shorter-rooted varieties, sow thinly across the surface, thin lightly, and keep the container evenly watered — container mixes dry quickly and drought followed by watering splits the roots.
Rotation and companions
Grow carrots on a fresh patch each year, avoiding ground recently manured or used for carrots, to reduce pest and disease build-up. Some gardeners interplant with onions or grow carrots among taller crops in the belief the stronger scents help mask the carrot smell from carrot fly; a physical mesh barrier is more reliable than any companion.
Storing carrots
Maincrop carrots store well. In mild areas leave them in the ground under a thick mulch and lift as needed; elsewhere lift before hard frosts, twist off the tops, and store undamaged roots in boxes of just-damp sand somewhere cool and frost-free. Damaged roots do not keep — use those first.
Sowing tiny seed evenly
Carrot seed is small and easy to sow far too thickly, which then forces heavy thinning — the very thing that attracts carrot fly. Two tricks help. Mix the seed with a little dry sand before sowing so it spreads thinly along the drill, or use pelleted seed, which is clay-coated into larger, easy-to-space pellets. Some gardeners even “fluid sow” pre-chitted seed in a gel. However you sow, aim to space seed well enough that only minimal thinning is needed, water the drill before sowing in dry weather, and keep it evenly moist through the slow two-to-three-week germination.
Planning a continuous supply
For carrots over a long season, sow small batches every three to four weeks from spring into midsummer rather than one large sowing. Early, quick varieties give tender summer carrots; a maincrop sowing in early summer matures for autumn lifting and winter storage. Spacing the sowings also spreads the risk from weather and carrot fly, so a single bad spell never wipes out the whole crop.
Related guides
Part of our Vegetable Gardening guides.
Related guides
Part of our Vegetable Gardening guides.
