Parsnips are a slow-growing root crop used primarily for winter storage. We grow parsnips in the third part of the rotation, and as long as the soil is deeply prepared there is likely to be little problem growing them. Plant as soon as the ground can be worked in spring, setting the seed 1/4 to 1/2 inch deep in rows eight to twelve inches apart, and thinning the plants to stand four to six inches apart once the second set of true leaves appears.
Since parsnips are slow to germinate, a little radish seed sprinkled in the row will help them break ground and provide a free harvest of radishes. The leaves of parsnips look a bit like those of celery. The roots will not be ready for harvest until the late fall, and many gardeners leave them in the ground through the winter, as the cold weather sweetens them considerably. If you want to keep the ground from freezing so they are easier to dig in mid-winter, put a wire quonset over the row, fill it with leaves, and clamp a piece of plastic over the top to keep the leaves from packing down with snow.
The standard parsnip cultivars are Harris Model and Hollow Crown. If you want to try one of the newer hybrid parsnips, Javelin is a good choice.