Parsnip

Sowing: Parsnip is direct-sown 3–5 weeks before the last expected frost, with seed set 1.3–1.9 cm deep and thinned, once seedlings reach about 2.5 cm tall, to a final spacing of 5–10 cm within rows spaced 46–61 cm apart. Soil should be worked to a depth of at least 30 cm and cleared of rocks and hard lumps beforehand, with compost rather than fresh manure added, since manure can cause the roots to fork.

Growing conditions: The crop favors a well-draining, loose, sandy soil with a pH of 5.8–7.5, full sun, and a cool growing temperature of roughly 15.6–18.3°C, tolerating some light shade but not summer heat. Plants need about 2.5 cm of water weekly, benefit from mulch to conserve moisture and suppress weeds, and are typically fertilized five to six weeks after sowing.

Parsnip is vulnerable to several fungal and oomycete problems, including cavity spot, which produces sunken gray lesions and cracks on the root, and damping-off, which rots seeds or collapses seedlings in cool, wet soil. Downy mildew appears as yellow spots on leaf tops with a fluffy white growth beneath, while Itersonilia canker causes necrotic leaf lesions and reddish-brown cankers on the root crown.

Management relies on cultural practices: rotating away from other umbelliferous crops, using pathogen-free seed, avoiding poorly drained soil, keeping root shoulders covered with soil, and removing crop debris and weeds. Carrot fly and other insect pests also attack the crop, with canker described as the most serious disease overall.

Harvest: Parsnip roots are best left in the ground until after the first light frosts of fall, when freezing converts starch in the root to sugar for a sweeter flavor; the crop should be dug before the ground itself freezes solid, or protected with covering if left in place over winter. Roots are lifted by loosening the soil around them and pulling gently but firmly from the top, after which the tops are twisted off before washing.

Storage: Washed roots can be kept refrigerated in airtight bags or packed in moist sand, and are commonly held cold, between about 32° and 40°F, since parsnips wilt quickly if allowed to dry out.

Handling: Because the plant's foliage and sap contain compounds that can sensitize skin to sunlight, gloves and long sleeves are recommended when harvesting to avoid a rash from contact.

Culinary: Parsnip roots are eaten cooked, most often boiled, roasted, mashed, or pureed, and are also sliced into crisps; the young leaves can be cooked and eaten as a vegetable, and the seeds have been used as a dill-like seasoning. The root has long been noted for its sweet flavor, and before cane sugar became available in Europe it was used as a sweetener.

Historical: Parsnip roots have also been fermented into beer and wine.

Parsnip is native to Eurasia, with a center in the Mediterranean, and has been used as a vegetable since antiquity. It was cultivated by the Romans, though ancient writers sometimes confused it with carrots, and it later spread across Europe before being carried to the Americas by European settlers in the early 17th century, where it subsequently became naturalized.