How to grow carrot

Plan this 3–4 months before you sow, right down to about a month before. Pick a field where no carrot, parsnip, celery, parsley or coriander has grown for at least 3 years — they all feed the same soil pests, so a long gap breaks the cycle.

Favour land that grew a cereal or a legume last (like maize or beans) — these leave the soil clean of carrot pests and in good heart.

Choose deep, light, stone-free ground — a sandy loam is best. Avoid heavy clay, shallow soil, or land full of stones and old roots, where the roots fork and stub.

Keep off any field that had fresh manure recently, and off low, wet spots — both bring the forking, hairiness and root rots carrots hate. Jot down what grew in each field each year, so you can plan the 3-year break without guessing.

In the last 3 weeks before sowing, buy fresh, certified carrot seed from a registered dealer — a sealed, labelled packet with this season's date. Carrot seed loses its life fast, so old or loose seed comes up thin and patchy.

Buy the variety, seed rate and fertiliser your recommendation gives for your field. Carrot lives mostly on potassium (K) and phosphorus (P) and wants only a little nitrogen (N) — too much N forks the roots and grows leaf instead of carrot.

If your recommendation includes a little boron (B), buy that too. Carrots are one of the few crops that often need it, and a boron shortage leaves the roots cracked, corky and brown in the middle.

Store seed and fertiliser dry, off the floor, and away from food, water and children. Keep the label and receipt in case the seed turns out poor.

In the month before sowing, dig or plough deep — about 20–30 cm, a full spade blade and a little more — and break through any hard layer (a 'pan') underneath, so the root can drive straight down.

Then rake the top down to a fine, crumbly surface (a 'tilth') — break every clod to about pea size. The tiny seed can't push through big clods, and clods leave air pockets that fork the roots.

Pick out stones, old roots and hard clods as you go — anything solid in the top 25 cm (about a spade's depth) becomes a forked or split carrot.

Finish with a level, lightly firmed surface — firm enough that your footprint barely dents it — so the tiny seed sits snug against moist soil and the bed doesn't dry into cracks.

Use only well-rotted compost — dark, crumbly, no strong smell. If it still smells of dung or you can see straw, it is not ready; keep it off the carrot bed.

Spread a light, even layer and work it into the top few centimetres — a thin skin over the bed, not a heap. Carrots want steady, gentle ground, not rich ground.

Do this in the 1–2 weeks before you sow, once the bed is dug fine, so it settles evenly into the soil.

Sow into a fine, firm, moist bed. Mark shallow rows about a hand-span apart (≈20 cm) — a little closer or wider (15–30 cm) is fine — and keep them straight so weeding and thinning are easy.

Sow shallow — about 1–2 cm, no deeper than a fingernail — and cover with just a fine scratch of soil. Deep seed rots before it reaches the surface.

Sow thinly and evenly along the row. The seed is tiny, so mix it first with a handful of dry sand — it spreads more evenly and saves you heavy thinning later.

Firm the soil down gently over the seed with the back of a rake or your hand, so the seed touches moist earth.

Water gently straight away with a fine rose, and from now keep the top 3–4 cm always moist — the sprout is slow (1–3 weeks), so the bed must never dry out (see the watering task).

From about a week after sowing, walk the rows twice a week and look closely at the seedlings and the spaces between them.

Damping-off (a seedling rot): look for seedlings that have toppled over, pinched and dark-wet where the thread-thin stem meets the soil, and small bare patches where seedlings rotted before they even showed. It spreads in wet, crusted, over-watered beds.

Cutworms: look for seedlings cut clean off at ground level, lying wilted on the soil (worst overnight). Scratch the soil a few centimetres around a cut plant to find the fat, grey, curled-up caterpillar.

Note the bare gaps as you go. While the crop is only a week or two old and the soil is still moist, you can re-sow the worst patches with seed — do it now, before the row ages.

From sowing until the seedlings are up (about 3 weeks), keep the top 3–4 cm of soil always moist — damp down to about your first finger-joint.

Water little and often — every 1–2 days, more in heat — with a fine rose or gentle spray, never a hard splash that washes the seed out or beats the surface into a crust.

Check by touch: if the top 3–4 cm is starting to dry, water again. The bed should feel like a wrung-out cloth — never dust-dry, never sodden.

Water in the cool of morning or evening, so less is lost to the sun and the surface stays damp longer.

From 3 weeks after sowing through about 6 weeks, walk the crop twice a week, looking over the leaves and pulling a test root or two to check underground.

Alternaria leaf blight: look for dark brown-to-black spots with a yellow halo, starting at the edges of the older, outer leaves; badly hit tops look scorched and blackened.

Cercospora leaf blight: look for smaller grey-tan spots with a dark ring, more on the younger leaves and the leaf-stalks.

Carrot fly: look for tops that turn reddish-bronze, stunted and wilty; pull a test root and check for rusty-brown tunnels and scars just under the skin.

Aphids: turn a few leaves over and look for colonies of tiny soft green or grey insects, sticky shiny honeydew (their sugary droppings), and ants running up the plants.

Note what you see and where, and act at the first clear sign — open the matching pest or disease guide. A carrot can't outgrow damage the way a taller crop can.

Thin about 3–4 weeks after sowing, once the seedlings are a few centimetres tall and you can handle them — the earlier the better.

Pull out the extra seedlings so the ones left stand one every 3–5 cm — about a finger-joint apart along the row.

Thin when the soil is moist, and firm the soil back around the roots you keep, so no gap is left open for carrot fly to lay its eggs.

Thin in the cool of the evening and carry the thinnings right away — the smell of bruised carrot leaf is exactly what draws carrot fly to your crop.

Weed early and by hand, from about 3 weeks after sowing, while the weeds are still small and easy to tell from the ferny carrot tops.

Weed shallowly and close to the plants — carrot feeder roots run near the surface, and deep hoeing beside the row cuts them and lets in rot.

As you weed, draw a little soil over any root tops that show green at the shoulder — this stops them going green and bitter, and hides them from carrot fly.

Keep the bed clean until the carrot tops meet over the row and shade the ground; after that the crop holds its own.

About 4–5 weeks after sowing, once you have thinned and weeded, give the moderate amount of nitrogen your recommendation sets — no more (excess forks the roots).

Band it in a thin line along each side of the row, a hand's-width off the plants — not over the tops — so it feeds the roots and doesn't scorch the leaves.

Feed when the soil is moist (after watering or light rain) and water it in, so it reaches the roots instead of gassing off into the air.

Keep fertiliser off the wet leaves — grains that stick will scorch them. Wash your hands afterwards, and keep it away from food, water and children.

From 3 to 6 weeks after sowing, water every 3–5 days to keep the soil evenly moist down to the young roots — more often in heat and on sandy soil.

Water deeply enough to wet the root zone, then let the surface dry just a touch before the next watering — steady and even, not a flood then a drought.

Check by pushing a finger in: water when the top few centimetres start to dry, before the plants wilt.

From 6 weeks after sowing, walk the crop once a week and pull a few whole roots from different spots to check them — the leaves look fine long after the root is spoiled.

Cavity spot: look for small, sunken, oval grey-brown pits across the root skin — worse in wet, cool, poorly drained soil.

Root-knot nematode (a tiny soil worm): look for knobbly swellings and galls on the roots, and forked, hairy, stunted carrots in yellowish patches of weak plants.

Carrot fly: keep checking pulled roots for rusty-brown tunnels just under the skin, and tops that look reddish and stunted.

Splitting: look for lengthwise cracks in the roots — the sign of a sudden drink after the soil went dry. Bolting: look for a flower stalk shooting up from the centre; that root turns woody and bitter — pull and use those ones early.

Feed potassium about 6–8 weeks after sowing, just as the roots begin to swell — the amount your recommendation sets.

Band it in a thin line along each side of the row, a hand's-width off the plants, and water it in on moist soil.

Keep nitrogen off now — late nitrogen delays colouring and shortens storage life. Potassium (and any boron (B) your recommendation gives) is the feed that counts at this stage.

Keep fertiliser off the leaves and out of any cracks in the soil; wash your hands afterwards, and keep it away from food, water and children.

From 6 weeks after sowing through root-swelling, water deeply and evenly every 4–6 days, wetting the soil right down into the root zone (carrot roots reach about 75 cm deep).

Aim for a steady rhythm — soil that stays evenly moist, never swinging from dust-dry to soaked.

In a hot, dry spell, water a little more often rather than one big flood — the flood after dryness is exactly what cracks the roots.

Ease back only near harvest (see the last light watering task before you lift).

From about 90 days (3 months) after sowing, pull a few sample roots from different parts of the bed to judge them.

Check the shoulder (the top of the root at soil level): it should be full-sized, about 20–30 mm across — roughly a thumb's width — and the whole root a firm, full, even colour right down.

The root should feel firm and full-length when pulled — not thin, stumpy or soft.

When most sample roots pass, the crop is mature — go ahead and lift (see the harvest tasks).

If the sample roots are still small, pale or thin → don't lift yet. Keep the moisture steady and even, and test-pull again in 1–2 weeks until the shoulders reach full size and colour.

About a week before you plan to lift (roughly 15 weeks after sowing), give the bed one last light watering — just enough to soften the soil, not to flood it.

Let the surface drain back to moist-but-not-wet before you lift — you want soil that crumbles off the roots, not sticky mud.

Lift at about 110–130 days (roughly 3½–4½ months) after sowing, on a day when the soil is moist but not wet.

Loosen first, don't yank: push a fork or spade in beside the row, a little away from the roots, and lever the soil up to free them — pulling hard on dry ground snaps the root and leaves the tip in the ground.

Hand-pull the loosened roots by the tops, shaking off the soil. Handle them gently — bruises, cuts and broken tips all rot in storage.

Lay the lifted roots in the shade, not the hot sun, and go straight on to topping, washing and cooling the same day (see the next stage).

Top them: break or twist off the leaves close to the crown as soon as you lift — leaves left on draw water out of the root and it wilts.

Wash the soil off with clean water, changing the water often so you are not just re-coating them in mud.

Grade as you go: set aside any root that is cut, bruised, split, forked or soft — these rot first and will spoil the sound ones beside them. Use or sell the damaged ones quickly.

Soft-rot check: throw out any root with a soft, wet, slimy, foul-smelling patch (usually starting at a wound) — it spreads to its neighbours in the store.

Cool them the same day, out of the sun. Kept cool and damp (around 2–3 °C, very humid — 90–95%), sound carrots hold for up to 6 months; left warm, they soften in days.