How to Grow Carrots from Seed (Daucus carota)

Carrots are the crop that persuades people they cannot grow vegetables. The seed sits in the ground for three weeks and nothing happens; the row comes up patchy; the roots fork, split, or come out riddled with rusty tunnels. None of it is bad luck. Carrots simply have a few rules of their own — about soil, about thinning and about one small fly — and once you know them they are among the cheapest and most reliable crops on the plot.

Daucus carota is a biennial from the same family as parsnip, parsley and celery. In its first season it stores sugar in a taproot; in its second it flowers, which is why the lacy "wild carrot" in the flower border is the very same species. Everything below is about that first season — and about two jobs for early September: sowing a fast variety under cover for finger-sized carrots in late autumn, and lifting and storing the maincrop.

• Botanical name Daucus carota subsp. sativus — carrot family (Apiaceae), biennial grown as an annual
• Sow Feb–Mar under cover · Apr–Jul outdoors · early Sept and Oct–Nov under glass for baby carrots
• Germination 14–21 days at 10–20 °C — slow, and the seed keeps only 2–3 years
• Spacing thin to 4–5 cm (7–8 cm for storage types), rows 25–30 cm apart

Choose the variety for your soil, not the picture on the packet

A carrot root is shaped by the ground it grows in. The long, tapered types — Berlicum, Flakkee, Autumn King, the classic Dutch winter carrots — need deep, light, stone-free soil. On heavy clay or a stony allotment they fork, twist and stop short. For that kind of ground choose a stump-rooted or round variety: broad-shouldered Chantenay, the little round Paris Market, or the short cylindrical Amsterdam types bred for sowing in frames (bak is Dutch for frame). Nantes sits in the middle — smooth, blunt-ended, sweet, and the best all-rounder for medium soil and containers.

The catalogue split into summer carrots and winter carrots is Dutch, and worth understanding. Summer carrots (Amsterdam, Nantes, Paris Market, Napoli F1) are fast and tender, for pulling young. Winter carrots (Berlicum, Flakkee, Autumn King) are sown later, grow larger and are the ones you store. Carrots were purple and yellow for two thousand years; the orange carrot was selected in the Netherlands in the seventeenth century, and Purple Sun, Yellowstone and the rainbow mixes are simply the old colours coming back.

Soil: the one thing you cannot fix later

Carrots want soil that is fine, deep and settled — forked over in winter, raked to a fine tilth in spring, and not manured within the past year. Fresh manure or a strong nitrogen feed makes roots fork and throw hairy side roots, and gives you a bed of magnificent leaves. The ideal spot is the bed that was manured for last year's hungry crops, which is exactly why roots follow the greedy feeders in a crop rotation. On heavy or stony ground, grow in a raised bed filled with a sandy mix, or in a deep pot — both also lift the crop above the worst of the carrot fly. Our guide to preparing your soil covers the groundwork.

Sowing carrots from seed, step by step

1. Wait for the soil to warm Carrot seed will not germinate below about 7 °C, and a sowing into cold, wet ground simply rots. Start under fleece or a cloche from late February, outdoors from April. Seedlings that sit through a few cold weeks can read it as winter and bolt in summer — early varieties resist this, maincrops do not.
2. Sow thinly in a shallow drill Draw a drill 1 cm deep — deeper than 1.5 cm and the seedlings never surface. Sow in pinches from your palm, or mix the seed with dry sand; rows 25–30 cm apart. Seed tapes and pelleted seed exist for one reason, perfect spacing without thinning, and step five explains why that matters. The technique is in our guide to direct sowing.
3. Keep the drill moist for three weeks Carrot is slow, and a drill that dries out in week two stops germination halfway — that is where most patchy rows come from. Sow a few radish seeds along the drill as a marker: up in five days, they show you the row and are pulled long before the carrots need the space (see how to grow radishes).
4. Sow little and often A short row every three weeks from April to July keeps you in fresh carrots from June to Christmas — classic succession sowing. The last outdoor sowing of a winter carrot goes in by late June. Then sow a fast type under a cloche in the first half of September, and again in October or November in a greenhouse border or cold frame for the earliest carrots of spring.
5. Thin in the evening, and water afterwards Bruised carrot leaves release the scent that brings the carrot fly, so thin at dusk when it is not on the wing, firm the soil back, water the row, and take the thinnings indoors rather than to the compost heap. Better still, sow thinly enough that you barely thin at all.
6. Cover against carrot fly Fine insect mesh over hoops, sealed at the soil, from sowing to harvest is the only method that works every year. Move the carrots to a fresh bed each season; the pupae overwinter where last year's crop stood.

Carrot fly: why thinning is the moment that matters

The carrot fly lays its eggs at the base of the plant and the larvae tunnel through the root, leaving the rusty tracks every grower recognises. There are two generations, roughly May–June and August–September, so a sowing made in late May and harvested by August slips between them, and a September sowing under cover misses the second flight altogether. The fly hunts by scent — which is why crushed leaves at thinning time matter, why a row of onions or leeks alongside is one of the few companion planting pairings with real evidence behind it, and why the famous "60 cm barrier" is only half true: the fly does stay low, but wind carries it over a fence. Resistant varieties such as Flyaway F1 are less attractive to the fly rather than immune, and still want covering in a bad year. Our guide to common garden pests covers the rest of the cast.

Water, weeds and the split-root rule

Steady moisture matters more than quantity. A dry spell followed by a heavy soaking makes roots split, because the core grows faster than the skin can stretch. Water deeply once a week in dry weather rather than a little every day, and mulch between the rows once the tops are 10 cm high. Weed by hand while the seedlings are small: a hoe drawn close to the row slices the roots. Draw soil over any shoulders that push above the surface, which turn green and bitter in the light. And do not feed — the fertility left by last year's crop is enough, and nitrogen grows leaves, not roots.

Harvesting and storing carrots

Pull summer carrots as soon as they are finger-thick, ideally after watering so the soil lets go; on heavier ground ease them out with a fork or the top snaps off in your hand. Winter carrots are lifted in October or November on a dry day. Twist the tops off close to the crown, rub off the soil without washing, and pack the undamaged roots in boxes of barely damp sand, not touching, in a cold shed or garage at 0–4 °C — they keep four to five months. On light, well-drained soil you can leave the crop in the ground under 15 cm of straw and lift as needed, but slugs and late fly larvae feed all winter, so the sand box is the safer store. Our guide to harvesting and storing your produce covers the general conditions.

Common mistakes

• Sowing into freshly manured ground. Forked, hairy, leafy carrots. Manure the bed for the previous crop, not this one.
• Sowing thickly and thinning at midday. The fly finds a row of bruised leaves within the hour. Sow thinly, thin at dusk, water afterwards.
• Letting the drill dry out in week two. Germination stops halfway and you blame the seed.
• Using old seed. Carrot seed loses vigour quickly; after two or three years germination is poor and slow. Test it with our guide to how long seeds last.
• Growing long carrots on stony clay. Choose Chantenay, Paris Market or an Amsterdam type, or grow in a raised bed or deep container.

Frequently asked questions

Can I still sow carrots in September?
Yes — a fast Amsterdam or Nantes type sown under a cloche, in a cold frame or in a greenhouse border in the first half of September gives sweet baby carrots from November. Growth slows with the shortening days, so expect finger-sized roots rather than a maincrop. A sowing under glass in October or November sits through winter and gives the earliest carrots of next spring.

Why did my carrots fork?
Fresh manure, stones, compacted soil, or damage to the root tip from a pest or from transplanting. The root tip sets the shape in the first fortnight, so never transplant carrots — always sow direct, into fine, settled soil.

How do I stop carrot fly without chemicals?
Mesh from sowing to harvest, thinning in the evening, sowing after mid-May for a July harvest, rotating the bed each year, and growing in containers or beds well above ground level. Onions alongside mask the scent and help, but will not do the job alone.

Why won't my carrot seed germinate?
Cold soil below 7 °C, a drill that dried out, seed sown deeper than 1.5 cm, or seed that is simply too old. Carrot is slow by nature — give it three full weeks before you decide, and see our guide on why seeds fail to germinate.

Carrots reward patience at the start and restraint afterwards: fine soil, a shallow drill kept moist, a thin sowing, and a mesh cover instead of a spray. Start with a packet of carrot seed from the botanical Daucus carota range — including organic carrots — and add their cousins parsnip and parsley, which want the same soil and the same rotation, plus onions and leeks for the row alongside. While you are lifting the maincrop, our companion piece on when to harvest pumpkins and winter squash covers the other crop to bring in and store this month. Browse everything you can still sow in September and October, plan the spring sowings from March, and explore the full root vegetable and vegetable seed collections or the organic range. For more, dig into our growing guides library or the beginner's guide to growing vegetables from seed, or browse all seeds.