Parsnips don't appear high on most gardeners' "must-have" list, which is too bad. They are a delicious spring vegetable that's ready to harvest even before the first spinach. That's right, parsnips will survive the winter right in the ground – even in the coldest parts of the country. They sweeten up during the cold months, converting starches to sugars, so they taste best when dug up in very early spring, just as soon as the ground thaws. Parsnips taste a bit like carrots and resemble them in many ways.
Plant parsnip seeds directly in the garden about half an inch deep, early in the spring. Always use fresh seed. Prepare the soil by digging deeply – the roots can grow a foot or more long – and adding compost or aged manure. Parsnips need lots of nitrogen, but only small amounts of phosphorous and potassium, so you can use dried blood to increase nitrogen levels without boosting the others. Or use any all-purpose organic fertilizer. Parsnip seeds take two to three weeks to germinate, during which time it is important not to let the soil dry out. Thin to 3-4" apart and mulch the soil to stifle weeds and help keep the soil evenly moist.
Parsnips are slow-growing. Count on 150 days from planting to maturity. You can pick them earlier, of course, but they will be smaller and less tasty. You can interplant with fast-growing plants, such as radishes, which will be ready to harvest while your parsnips are still small. In the spring, pull your parsnips before they begin to send out green shoots at the top. Like carrots, parsnips are biennials and will quickly go to seed once they begin growing their second year. Harvest overwintered parsnips quickly, before the roots begin to soften and produce foliage.
A mature parsnip looks like a pale, ugly carrot. Unlike carrots, the bigger the parsnip the better. Their texture is more fibrous than a carrot so they're rarely eaten raw. But when cooked – and especially roasted – parsnips overcome their homely appearance and become a vegetable treat without par.