11 tips for growing parsnips

• Parsnips have a very long growing season, occupying ground for nearly a year, so think carefully about where to plant them. Choose a sunny site well away from trees.

• Parsnips yield well in average conditions but prefer a friable, welldrained and deeply-dug soil, especially for long varieties which can grow up to 30cm. A well-manured soil for a previous crop works well - fresh manure causes forked roots. A dusting of wood ashes (potash) is beneficial.

• Sow from September to March in the North Island and October to December in the South, and use fresh seed as it loses viability quickly. Sow thinly 1-2 cm deep and 1cm apart in rows 30cm apart.

• Germination can take 21-28 days and is improved if rows are kept moist for the germination period.

• Thin plants to 3-5cm initially, then to 10-15cm or more for larger varieties. Use thinnings for soups, stews and stir-fries.

• The tops resemble a large, broad-leaved parsley plant and once established they grow vigorously to 30-60cm high, needing little attention apart from an occasional hoeing between rows. Mulching can help control weeds and conserve moisture.

• Parsnips can be attacked by carrot fly, which feeds on the outer layer of the roots. The carrot fly is attracted by the smell of bruised tissue so damage can be minimised by sowing thinly, providing good growing conditions, and weeding carefully.

• Parsnips are ideal for southern gardens as they are one of the few vegetables which benefit from frost. Cold weather causes starches to convert to sugars giving a richer, sweeter flavour.

• The roots can be left in the ground all winter and dug as needed, an advantage as stored roots can shrivel and develop a woody core. Once dug, the tops should be trimmed close to the core to prevent loss of moisture. In warmer areas you should lift them as they mature.

• Pulling long parsnips can result in a handful of top and no root. The best way to is to dig a trench, beginning at the end of the row, and pull the roots towards you.

• Choose a strong parsnip plant for next season’s seed. Parsnip is a biennial, so it flowers in its second season. The yellow flowers are born in umbels up to 10cm across at the ends of long stems. As the seed matures it turns pale brown - this is the time to harvest. Cut seed heads and finish ripening in a paper bag in a dry place.