|'Cobham Improved Marrow' has a long root with smooth skin. This variety is quite resistant to canker. A hard winter will make for wonderfully sweet parsnips.
Parsnips like deeply tilled, light soil with a pH of about 6.5. Acidic soil will encourage cankerous roots. Germination can be slow, taking up to 3 weeks, but can be improved if you warm the soil with a plastic cover. Sow seed 1/2 inch deep in rows 1 foot apart. If parsnips are watered after a long dry spell, the roots may split, so water them regularly. Harvest the crop from mid-autumn through the winter.