How to grow carrots

Follow our detailed Grow Guide to growing carrots, below.

Growing carrots from seed

There are two types of carrot to choose from – early varieties, which are sown in spring and are ready to harvest about 10 weeks later, and late varieties, which can be sown from the end of spring and are ready to lift after about 14-16 weeks.

When to plant carrots depends on your growing space and the materials you have to hand. The main carrot sowing season is late March to June, but earlier and later sowings can be achieved by sowing in a greenhouse or polytunnel, or on soil that has been pre-warmed beneath horticultural fleece or a cloche.

Good soil preparation is essential. Fork it thoroughly to break up lumps and remove as many stones as possible. Carrots thrive in light, well-drained but moisture-retentive soil, but can 'fork' if the nutrient value of the soil is too high. For this reason it's best to not add organic matter to the soil the year you use it for growing carrots – add organic matter the year before, instead.

If growing carrots in the soil, sow seed directly. Make a seed drill (shallow trench) about 1cm deep using the edge of a hoe or trowel. Sow the seeds thinly along the bottom of the drill about 5-8cm apart – be careful not to grow carrots too close together as this can stunt their growth. Cover the seed with a thin layer of sieved soil, and water well using a watering can with a rose attached.

To extend your cropping period, sow seeds successionally at two-week intervals. Sow a selection of carrot varieties that will crop at different times over the season.

Here, Monty Don demonstrates how to sow carrot seed, explains how to deter carrot root fly and suggests easy ways of identifying carrot seedlings:

Growing carrots in containers

Carrots do well in containers – indeed, carrots can be difficult to grow in heavy or stony soil, so they can do better in containers than in the ground. Your carrot planter can be anything from a 30cm terracotta pot to an old recycling bucket, you can even buy bespoke carrot planters specifically for the job. Most carrots need a depth of around 30cm to grow, so a container with a minimum depth of 30cm is ideal. However, you can choose round-rooted or dwarf carrot varieties for shallow containers, or remember to harvest longer types early so they don't reach the bottom of the pot.

Fill your carrot planter with sifted garden soil or a loam-based compost such as John Innes No. 2. Water the compost first and allow to drain, and then sow carrot seeds thinly, covering lightly with sieved soil.

Carrots in containers don't need much more attention than those growing in the ground but you will need to water them more often, especially in dry weather. To prevent carrot root fly you can simply cover the whole container with horticultural fleece, weighing it down so the fly can't access the carrot plants to lay her eggs. When harvesting carrots, water the compost first to soften it, which will make pulling the carrots out easier.

Here, Monty shows you how to sow carrot seed in a container:

Caring for your carrot crop

Carrots don’t require too much care. Aim to keep the soil around them weed free, although once the they start to grow strongly, their foliage will shade out most weeds. Water occasionally – you want the roots to grow long so too much watering will result in stunted growth, because the roots will get everything they need near the soil's surface.

Carrots that are flowering are a sign that the crop has bolted, often because of unseasonably warm weather. You can either leave the flower to provide food for bees and other pollinators or remove the plant from your row, but the carrot will no longer be edible once the plant has flowered.

To prevent your crop from bolting, grow in a spot that doesn't get full sunshine during the heat of the day, and water when temperatures start to increase.

Thinning out carrot seedlings not only wastes time, it can also attract carrot root fly because they will detect the smell of crushed foliage when you pull the carrot seedlings up. Carrot flies lay their eggs in the soil around carrot plants. The larvae then burrow into the carrot roots, eating and defecating in them.

Sowing thinly is therefore better than thinning after sowing, but if you do need to thin your carrots, don't worry. Here, Monty Don explains how to thin carrots while deterring carrot root fly:

Pests and diseases

Carrot fly is the most common and serious problem associated with growing carrots. The fly's maggots eat tunnels through the roots, ruining the crop. Choose resistant carrot varieties such as 'Resistafly', 'Flyaway' or 'Syrtan'. Alternatively, place a 45cm-high fine-mesh barrier around crops or cover with fleece or a similar material. Alternating a row of carrots with a row of companion plants like onions or garlic may help to mask their smell.

How to harvest carrots

Lift carrots when the soil is moist, or water beforehand, so they don't break apart when you pull them. Water the soil again to settle it around the remaining roots.

Watch Monty harvest carrots in this video:

How to store carrots

Storing carrots is a great way to deal with gluts and ensure you can enjoy fresh carrots throughout winter. On well-drained soils, carrots can be left in the ground, protected from frost by a thick layer of straw, bracken or soil. On wetter soils, the ground can become hard in winter, which makes harvesting difficult, so it's better to make a clamp.

A 'clamp' is made using horticultural sand and straw, and is the best way to store carrots. It protects the crop from frost in the same way soil does, but holds less water than soil, making harvesting easier. By making a clamp in autumn you can keep carrots fresh until early spring.

Choose a sheltered, dry site to make your clamp, and use carrots in good condition. Prepare your crop by shaking off loose soil and removing any foliage.

1. Use a spade to dig a shallow hole about 15cm deep and pour a 5cm layer of horticultural sand over the bottom. Lay out your carrots and then cover them with a second layer of sand, so you can no longer see any carrots
2. Cover the sand with straw and then cover the straw with soil
3. If you have a lot of carrots to store, you can make a larger clamp. Start by digging a circular hole then adding a layer of sand to the bottom. Create a ring of tightly-packed carrots, about a metre in diameter, with their necks facing outwards. Continue adding carrots to create a pyramid shape. Then add a 30cm layer of clean straw over the clamp. In cold areas, add a layer of soil for extra frost protection. Cover with plastic sheeting

How to save carrot seeds

As biennials, carrots flower and set seed in their second year. Seed production is an energy-intensive process and the carrot plant draws on carbohydrates stored in its root – this means the carrot is no longer edible once the plant has started to produce seeds.

If you grow open-pollinated (not F1) carrot varieties you can leave a few to flower and set seed, saving you the need to buy fresh carrot seeds the following year. In milder regions of the UK simply leave your carrots in the ground, mulching around the base of the plants to protect them from frost. The foliage will die back but will then regrow in spring, and then flowers and seeds will form.

In colder areas, dig up your carrots in autumn, remove the foliage and store them in a clamp (see above). You can then replant them in spring to sprout new leaves, flowers and seeds.

Keep an eye on your carrot flowers and snip off the whole head when they become brown and dry. Continue to dry the seedheads undercover (such as in your shed or greenhouse) until completely dry, and then use your hands to separate them from the plant.

You can sieve the seeds to remove any chaff (spent foliage and stems) but it's not strictly necessary for germination. Once harvested, carrot seed can last for up to three years.

Bear in mind that carrots can cross-pollinate with wild carrot (Daucus carota), which has small, thin, white roots. It's virtually impossible to isolate your crop from wild carrot (a distance of around 500m is recommended), so keep an eye out for white roots when you come to harvest your carrots, and ensure you don't save the seed of these.

Growing carrots: preparation and uses

Looking for inspiration on how to use your crop? Our friends at olive have curated a delicious collection of carrot recipes, including a carrot cake that uses muscovado sugar for a richer flavour.

Types of carrot to grow

• 'Amsterdam Forcing 3' – produces short, cylindrical roots
• 'Autumn King 2' – classic orange, late-maturing variety
• 'Nantes' – sweet, perfect for slicing
• 'Parmex' – a round-rooted carrot, perfect for growing in pots
• 'Purple Haze' – dark purple skin surrounds the orange flesh
• 'Resistafly' – resistant to carrot fly