Growing Parsnips from Seeds.
Sow in late March or April as germination is the trickiest part of growing parsnips, and seed sown too early is more likely to fail. If you are determined to sow earlier, warm the soil with cloches prior to sowing and leave the cloches in place until the seedlings have established. Sow 2-3 seeds together, half an inch deep, 6" apart in rows 12" apart.
Thin once the seedlings are approximately 1" high, leaving one plant per 6" apart. If you are short of space or want to grow smaller parsnips, sow closer together, 20cm apart and thin to about 8cm. Alternatively, selected parsnip varieties can be grown in containers which will produce mini roots.
An evenly moist soil will help prevent splitting so water if the weather is dry and apply a mulch to aid water retention.
Harvesting begins in September, once the foliage begins to die down and continues into the following spring. Roots can be left in the ground in the winter and lifted as necessary. Frosts improve the flavour but you may be wise to lift extra in November before the ground freezes. Lift the roots using a fork, being careful not to damage them. Parsnips can be stored in boxes of moist soil for up to a month, in a cool, dark place.