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Home grown (Filed: 30/06/2001)

How to grow your own food organically by Sarah Raven. This week: carrots

CARROTS can be a pain to grow. You sow the seeds, they germinate and grow well but, when you harvest them, half the roots are a warren of holes. The entrances to the warrens may be tiny, but they can hide cavities that leave little to eat. They also tend to fill with grit, so you end up with what feels like half the garden in your mouth.

It is easy to give up and buy carrots instead, but this year I am determined to eat my own, organically grown crop. These vegetables taste their delicious best when picked and eaten straight from the ground.

They have a characteristic flavour that is somewhere between parsley and celery, and is much sweeter, earthier and denser than shop-bought carrots.

So how can you guarantee to grow carrots without all the holes? The culprit is the carrot fly, a tiny, almost inconspicuous, beast that lays its eggs in the soil. It lives in sheltered places with good cover and a plentiful supply of nectar-rich food - an accurate description of most people's gardens in summer.

It is not a choosy pest and the maggots feed not only on carrots, but also on relatives such as celery, celeriac, parsnips, parsley, angelica and lovage.

The fly is attracted by the smell of carrots, which is at its strongest when you thin them out. The scent of crushed foliage as you pull seedlings from the ground is a delicious lure for the carrot fly.

Once eggs are laid and hatching, the maggots tunnel into the main root. Sometimes the attack makes the leaves of young plants redden and wilt but you might not notice any change.

Neither adults nor larvae are around all the time. There are two distinct seasons - one at the end of May and beginning of June, and another at the end of July and early August - when large numbers of flies are looking for places to lay their eggs.

This is when carrots are most at risk and it is why it is a good time to sow. Most of the first generation of flies will have died and, by the time the second generation emerges, a crop sown now will be well established and won't suffer so badly from an attack.

While sowing in late June will help protect your crop, the fly does not keep to an exact calendar, so this is not enough on its own to guarantee a completely clean line. You'll need a few other protective mechanisms up your sleeve to ensure a pristine, organic crop.

Carrots to grow

I grow my carrots for eating fresh, not storing through the winter. What I want is good flavour, crisp texture and, ideally, not too long a root as they do not do well on my heavy soil.

Orange

Amini A good carrot for eating young. It has a good flavour and is quick growing. I try to sow a line once a month so I have plenty to pick when they are still very small.

Primo An F1 hybrid that is an excellent quick-growing variety with good flavour. Sow it at almost any time.

Magno An organic F1 hybrid, very quick maturing with vigorous growth. It has done well in recent trials.

Fly Away An F1 hybrid bred with a lovely sweet flavour and some resistance to root fly.

Parmex or Parabell This is ideal for heavy clay soil where a long taproot will not get an easy run. It is also good for sowing early. It forms round carrots, good for eating when they are about the size of a golf ball.

Purple

There are one or two varieties available including Purple Dragon, originally from China. It looks superb, with a purple skin and orange core, but the flavour is not as sweet as most orange carrots.

Yellow

Yellowstone is a new variety in bright yellow. It has a slightly swedey taste, but looks good.

How to sow

Sow directly into the ground as thinly as possible. Space rows at least 12in apart. Keep the rows weed-free. Hoe between rows as soon as seedlings emerge, hand weeding between plants to avoid damaging the roots. After weeding, water in case you've uprooted or disturbed any carrots. A wilting plant gives off a stronger smell. Water if it's dry and apply a seaweed liquid feed every two to three weeks.

Where to buy seeds

The Organic Gardening Catalogue 01932 253666; www.organiccatalog.com S E. Marshalls 01945 583407

How to avoid carrot fly

Never sow carrots on ground that has recently been used for carrots, parsnips or any of their umbellifer relations. There may be maggots or pupae still in the soil, waiting for a new crop.

Create a physical barrier against flies by covering the seeds with horticultural fleece or fine-mesh netting. Fleece is best for an early crop, grown in cool conditions and harvested quickly. Use fine polypropylene netting at this hotter stage of the year. It allows more air circulation.

Put on the cover when you sow, allowing plenty of slack. You can let it out as the crop grows. Leave the cover on into the autumn, removing it only when you finish harvesting. The netting can be annoying when you have to weed or harvest, but it is guaranteed to save your crop from attack.

If you think fleece and mesh are ugly, there are other things you can do to protect your crop, but they will not work alone. Grow a carrot resistant to the pest. `Sytan' from Marshalls and `Flyaway' from Thompson & Morgan have shown partial resistance in tests. The roots contain a reduced level of chlorogenic acid, which the larvae need for survival. Avoid thinning the carrots by sowing pelleted seed, which is encased in a dissolvable shell. Every seed is triple the usual size and you can plant them an inch apart so they will not need thinning. Alternatively, sow seed through a cake-icing piper with a small metal nozzle. Mix the seed with wallpaper paste - the innocuous kind without fungicides - load it into the piping bag and squeeze it into a shallow trench, 2-3in wide. The seed will be well dispersed. Try sowing in 8in wide stripes. Clear the soil in a wide trench about .5in deep and sow the seed quickly. Over a larger area, it is easier to get thin and even distribution so the seedlings can grow on without thinning. Make it harder for the adult flies to lay their eggs by ridging the soil. When the carrots are large enough, draw up the soil about 2in either side of the row. Do this again six weeks later. Or you can mulch the rows with a 2in layer of grass mowings.

What does not work

A traditional organic way of protecting carrots from fly was to try to disguise their smell with a stronger one. Interplanting a line with onions was thought to be a good idea, but recent trials have proved it does not work for long.

Onions are a deterrent only when they are making leafy growth and have no effect once they have stopped sprouting. Even in the green phase, it takes four rows of onions to protect one of carrots.

-- Anonymous, July 06, 2001