Carrots
What to do
Soil preparation * Success with root vegetables is very much down to the quality of the soil that they're grown in, so it's worth taking the time to prepare your patch. Start digging over your soil in late winter or early spring, removing any stones you find and thoroughly turning the soil until it has a fine, crumbly texture. * If your soil is not ideally suitable for carrots or parsnips, you can prepare a large container for sowing instead. When digging over your soil, do not add manure as this makes the soil too rich for the seeds. * One week before sowing your seeds, rake in a light dressing of general fertiliser.
How to sow seeds * Carrot seeds are small, but it's wise to plant them as thinly as possible. This reduces the amount of thinning necessary and potential risk from pests. * Sow the seeds thinly on a sunny, dry day in shallow drills around 2-3cm (1in) deep, covering the seeds once in place. Early sowings in March and April may need to be protected with fleece or a cloche in some parts of the country. If you have difficulty sowing thinly, try mixing the seeds with a handful of sharp sand and then sowing the seeds and sand together. The sand will aid drainage and will allow thinner sowing. * Once the seeds have germinated and are showing their first rough leaves, thin the seedlings to 5cm (2 in) between plants. * Parsnips can be grown in a similar way, but as they're larger they should be thinned to 15cm (6 in) * The plants need little other attention during their growth period, although the plants should be kept well watered - too little water results in coarse, woody roots.
Leeks
What to do
Soil preparation * Choose a sunny, sheltered site with well-drained soil. * If possible, prepare the soil for planting in the winter. Dig the site well, removing weeds and working in plenty of well-rotted manure to improve its ability to retain water. * Leeks can be planted in heavy soil, but improve the drainage by mixing in some horticultural sand. * This is a hungry crop – spread a general balanced fertiliser over the soil a week or so before sowing and rake in. A rate of 60g per square metre is ideal.
How to sow * The easiest method is to sow seed directly into the soil between March and April. Alternatively, you could cheat and buy ready-grown seedlings, many nurseries offer a good range. By careful choice of varieties you could have an ample supply of leeks to harvest from mid-summer until the following spring. * On the allotment, seeds are best sown in rows, 30cm apart. Mark a straight line and use the corner of a rake to make a shallow groove in the soil, about 1cm deep. Sow seed thinly along the trench, cover with soil, water and label. When seedlings have three leaves each, about four to five weeks later, thin to leave plants every 15cm - the seedlings you remove could be used to plug gaps elsewhere. * Alternatively, buy ready-grown plants. They will arrive as young seedlings during May and June, ready to plant out straight away. To do this, make a hole with a dibber, 20cm deep, and drop a seedling into each. Using a watering can, fill the hole with water and allow to soak away - this will draw enough soil over the plant to cover the roots and produce wonderful blanched stems as the leek grows. * Keep plants well watered, especially during dry spells and harvest from summer onwards.
Onions and garlic
What to do
Soil preparation * A sunny, well-drained site is essential for growing good crops of onion and garlic. It's possible to grow good onions on heavy soil, but the drainage should be improved prior to planting with grit and bulky organic matter, and the cloves planted in ridges of soil 10cm (4in) high to help reduce soil moisture. * Onions and garlic both like fertile soil, but neither require much nitrogen and so shouldn't be grown on freshly manured soil. Instead, dig over and manure the ground several months before planting. If the soil is acid it's worth liming it so its pH level becomes neutral or even slightly alkaline.
How to sow seed * Sow seed in modules in January or February at 10-15°C (50-59°F). * Sow five or six seeds per module in damp seed compost - when planted out the clumps of bulbs will push themselves apart as they expand. * Cover seeds with a layer of vermiculite and label with variety name and date of sowing. * To have a year-round supply, you can sow once in spring for harvesting from August, and again in late summer or autumn to be ready from June, although a second planting isn't recommended in very heavy, wet soils. Onions should be given as long a growing season as possible to reach maximum size.