- Planting: Loosen the soil to a depth of 2 feet and remove rocks and clods. As soon as your soil can be worked, sow seeds 1/2 inch deep and 1 inch apart in rows that are 6 inches apart. Keep the seedbed evenly moist. Be patient. Parsnips can take more than two weeks to germinate.
- Spacing: When your parsnips are 6 inches tall, thin them to 3 inches apart. Put a layer of compost around the plants; then sit back and watch your crop grow until fall.
- Expert tip: Guarantee better germination by using a fresh packet of seeds (parsnip-seed viability drops off dramatically after 1 year) and soaking them overnight before planting.
Pest Watch and Disease Alert
Parsnips rarely experience disease or pest problems. Rotating your crop on a three-year cycle prevents scab (Streptomyces scabies), a disease that causes corky scabs to form on roots; and soft rot, which causes water-soaked spots on the leaves and roots. Carrot rust flies (Psila rosae) lay eggs near the crown of plants, and their larvae burrow into parsnip and carrot roots, causing rotting and reduced yields. Cover your seedbed with a row cover to keep these pests away from your crop.
Parsnips mature in about 120 days. But the roots taste sweeter if they're left in the ground until after the first hard frost. You can overwinter parsnips by covering them with a 2-inch layer of mulch. Harvest the roots as needed throughout winter and spring. Finish harvesting before new growth begins.