How to Grow Carrots (UK Guide)

From sowing to harvest — crisp, sweet roots every time.

Carrots are one of the easiest and most rewarding vegetables to grow in the UK. With the right soil and sowing times, you can harvest bright, flavourful roots from early summer right through to autumn.

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When to Sow Carrots in the UK 🪴

Carrots prefer cool, moist soil for germination.

• Outdoor sowing: March to June (southern UK can start earlier under cloches).
• Under cover: February onwards in modules or cold frames.
• Succession sowing: Every 3–4 weeks for a continuous harvest through summer.

Avoid sowing during prolonged cold or wet spells — carrot seeds are slow to germinate in cold soil.

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Preparing the Soil 🌱

Carrots grow best in light, stone-free, well-drained soil.
Heavy clay or compacted beds can cause roots to fork or twist.

1. Remove all stones and debris.
2. Loosen the top 25–30 cm of soil (don’t add fresh manure — it causes deformities).
3. Mix in sieved compost or sand if the soil is heavy.
4. Rake level and firm lightly before sowing.

Pro tip: For small gardens or clay soils, use a raised bed or deep container filled with sandy loam mix.

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How to Sow Carrots 🌾

1. Mark shallow drills about 1 cm deep and 15–20 cm apart.
2. Sow seeds thinly — roughly one seed every 2–3 cm.
3. Cover lightly with fine soil or compost.
4. Water gently and keep consistently moist until germination (7–21 days).

If seedlings are crowded, thin them once they’re 2 cm tall — final spacing about 5 cm apart.

Avoid thinning during midday or windy conditions to reduce carrot fly risk.

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Preventing Carrot Fly 🐛

Carrot fly is the main pest to watch out for in the UK.
Here’s how to prevent it:

• Grow resistant varieties: ‘Flyaway’, ‘Resistafly’, or ‘Maestro’.
• Use fine mesh or fleece barriers at least 60 cm high.
• Avoid thinning when flies are most active (late afternoon).
• Intercrop with onions, leeks, or garlic to mask the carrot scent.

Once roots are large enough, remove protective mesh only after the main carrot-fly season (late summer).

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Watering and Feeding 💧

Carrots don’t need much feeding — too much nitrogen encourages leaf growth over roots.

• Keep the soil evenly moist, especially during germination and dry spells.
• Avoid overwatering — sudden moisture after dry periods can cause roots to split.

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Harvesting Carrots 🌿

Most carrot varieties are ready 12–16 weeks after sowing.

• Early types (e.g. ‘Nantes’) from June.
• Maincrop varieties (e.g. ‘Autumn King’) into October or November.

Gently lift roots with a fork to loosen the soil, then pull by hand.

For the sweetest flavour, harvest after a light frost — the cold converts starches to sugars.

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Storing Carrots 🥕

Brush off soil and store in boxes of slightly damp sand or sawdust in a cool, dark shed.
Check occasionally for rot or pest damage.

Alternatively, leave carrots in the ground under a thick mulch through winter in mild areas.

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Common Questions ❓

When should I sow carrots in the UK?

March–June outdoors; in mild regions, sow under cover from February.

How do I stop carrot fly?

Use fine mesh barriers, choose resistant varieties, and avoid thinning when flies are active.

Why are my carrots forked or stunted?

Usually stony soil, fresh manure, or overcrowding early on.

Can I grow carrots in containers?

Yes — choose deep (30 cm+) containers, a sandy loam mix, and baby/round types like Parmex for tight spaces.

How deep should the soil be?

Aim for 25–30 cm of loosened, obstruction-free soil for straight roots.

How long do carrot seeds take to germinate?

Typically 7–21 days depending on soil temperature and moisture.

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Recommended UK Varieties 🧺

Type	Variety	Harvest Window	Notes
Early	Nantes 2	June–August	Smooth, sweet, fast-growing
Maincrop	Autumn King	September–November	Long roots, excellent storage
Resistant	Flyaway	July–October	Carrot fly resistant
Baby	Parmex	June–August	Round roots, great in containers

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Summary 🌼

Growing carrots in the UK is simple once you get the basics right — light soil, thin sowing, steady moisture, and carrot-fly protection.
Follow these steps and you’ll be rewarded with crisp, sweet, and perfectly formed roots all season long.