Sow successionally to give baby carrots in late spring and early summer followed by the main crop. Sow an early variety under cloches or in a sheltered position in the garden with the main crop sowings in mid to late spring. Sow the seed 0.5in (1.25cm) deep with the rows 6in (15cm) apart. Thin out in stages to 4-6in (10-15cm) apart.
Two 15ft (4.5m) rows of main crop carrots will give a yield of 60 to 80lb and the roots can be lifted from late summer onward. In favourable areas the crop can be left in the ground with a covering of straw or plastic sheeting and lifted as required.
The main pest of the crop is the carrot fly which lays its eggs alongside the plants. When they hatch the maggots tunnel into the roots causing the plants to wilt and, eventually, to die while the roots become riddled with holes.
The only effective control is to erect a barrier to prevent the fly reaching the crop. Woven plastic fleece can be placed over the seedlings or panels of polythene sheeting tacked to wooden frames can be erected round the rows. Using a resistant variety like Fly Away will also help to minimise the damage
Parsnip seed is very slow to germinate. Sow April to June, earlier sowings may attract canker. Sow in drills 1in (2.5cm) deep with the rows 12in (30cm) apart. Thin out gradually to one seedling every 5-8in (13-20cm). Some gardeners sow a quicker growing marker crop, such as radish, to indicate the position of the drills. Mature parsnips may be left in the ground over the winter for lifting as required or the entire crop can be lifted and stored in peat or sand.
These are a hardy root crop requiring an open site and a long growing period. Sow in late spring in drills 0.5in (1.25cm) deep and 18in (45cm) apart. Thin the seedlings to 6in (15cm) apart. Turnips and swedes are brassicas and should, if possible, be rotated with others of the family.
This is a dual-purpose vegetable: delicious when small and tender as a late spring crop; versatile and long-lasting as a winter vegetable. Choose a quick-maturing variety, such as Snowball, for sowing 0.5in (1.25cm) deep in rows 6in (15cm) apart in early spring. Harvest the roots when they are about the size of tennis balls and use the tops as spring greens. Sow the maincrop, such as the F1. Tokyo Cross, in mid-summer and thin the seedlings to 6in (15cm) apart. Keep the plants well watered in dry weather. Lift and store in late autumn as for parsnips.
Celeriac is hardy and requires rather less management then celery, so treat it as a root crop which can be stored in peat or sand for use throughout the winter.
Allow about 10-12 in (26cm) apart each way for celeriac plants and crops will need adequate moisture throughout the growing period. Celeriac should be lifted in late autumn and stored sufficiently.