The wild parsnip Pastinaca sativa is a native of northern Europe, including Britain, usually found on dry grassland and often on calcareous soils. The name 'Pastinaca' was originally given to the carrot, and it was only later it was transferred to the parsnip. It has been cultivated since at least Roman times; in fact Emperor Tiberius regarded parsnips so highly that he allowed Germany to pay part of its tax to him in them.
Sow seed fairly thickly in pre-watered shallow rows, and cover with a little soil. Allow about 40cm/16in between rows. Delay early sowings if soil is very wet or cold; later sowings will make up any lost time. As seedlings develop, thin them gradually, eventually to about 15cm/6in apart. Keep soil moist until seedlings are established.
Parsnips require an open position, growing best on light, but deep and well cultivated soils, ideally containing few stones. Having said that, they will grow satisfactorily on a wide range of soils. Do not, however, sow the seed on recently manured ground, as this will cause the roots to 'fork'. The addition of a general purpose fertiliser shortly before sowing will be beneficial.