Home-grown carrots can’t be beaten for flavour.
Pulled fresh from the soil, they fill the air with scent and provide that satisfying ‘crunch’ so often lacking in supermarket crops. Carrots are also rich in nutrients, containing high levels of vitamin A, beta-carotene and antioxidants.
Unfortunately, the rich scent of carrots attracts the attention of a pest called carrot root fly. Female flies lay their eggs at soil level near the shoulder of the carrot, and the larvae then eat into the roots. Early sowings are most vulnerable to attack, so delaying sowing of maincrop varieties until later in June will help protect them from root fly.
For an early crop, you’ll need to take other measures to prevent carrots being filled with holes and maggots. Discover how to grow carrots in our carrots grow guide.
Follow our guide to deterring carrot root fly, below.
Choose resistant varieties
Choose varieties that have been bred for their resistance to carrot root fly, such as ‘Flyaway’, ‘Ibiza’, ‘Maestro’, ‘Parano’, ‘Resistafly’ and ‘Sytan’.
Freshly harvested carrots
Avoid thinning out
Sow seed thinly to avoid having to thin out congested seedlings later on, because this releases a smell which attracts the pest.
Sowing carrot seeds
Cover with fleece
Cover vegetable beds with fleece, secured at the edges, after sowing carrots to prevent low-flying female flies reaching your crop.
Covering young carrot crops with fleece
Make fly barriers
Grow carrots in narrow beds surrounded with 60cm-high barriers of polythene, or fine-meshed netting – this is another good way to stop the female flies finding your crop.
Wrapping a fly-barrier around carrot plants in a tub
Grow with alliums
Grow carrots alongside strong-smelling companion plants such as alliums, including chives and garlic.
Growing carrots with alliums
Mix with other crops
Sow carrots among your vegetable crops rather than in large areas together, which makes it easier for pests to locate them.
Carrots growing beside rocket
Sow carrots late in the season – sowings made from June onwards usually avoid the first generation of pests, although further generations of flies can attack from July to September.
Sowing carrot seeds
Rotate your crops
Follow good crop rotation, growing carrots on a different site each year to avoid overwintering pupae in the soil hatching in the middle of your carrot crop.
Freshly harvested spring onions
Avoid parsnips and celery
Avoid growing related plants like parsnips and celery near carrots, as they also attract the pest.
Use a biological control, such as carrot fly nematodes, or a sticky trap.
Applying a treatment
Caring for your carrots
Carrots don’t require a great deal of care. Try to keep the soil around them weed free, although once the carrots start to grow strongly their foliage will shade out most weeds. Water sparingly.