Consistent care and pest protection are key to growing high-quality parsnips. Give them as much sun as possible and loose, sandy (but not rocky) soil that allows for deep root structures. They are a cool-weather vegetable, and temperatures over 75 degrees can affect growth and flavor. Provide 1-2 inches of water per week; drip irrigation ensures a steady supply, and light mulching will help retain the moisture. Weed regularly, especially when the plants are young.

As for pests, parsnip maggots/flies and leafhoppers are common; they can be controlled by row covers or insecticides. Excessively wet foliage can cause leaf blights, and not rotating crops often enough may lead to root rot and spotting.

Because of their long growing season and tap roots that don’t take kindly to transplanting, we don’t recommend starting parsnip plants indoors. However, you can “pre-germinate” the seeds so they grow faster once planted. Wrap the seeds in moist paper towels, then place them in a sealed container (such as a zippered food storage bag). Put the bag in a sunny area and mist the paper towels as needed to keep them moist. Temperatures of 50-70 degrees are ideal for germination, which can take up to four weeks.

Wait until soil temperatures are at least 55 degrees before planting parsnips. Seeds don’t keep well over the winter, so get fresh seeds and sow them roughly a half-inch deep. Space seeds 3-6 inches apart and rows at least 18 inches apart. Wait four years before replanting parsnips in a previous spot; any more frequently will increase the risk of pests and diseases.

To grow parsnips in containers, use well-draining planters that are a minimum of 15-20 inches deep and wide. Use square or rectangular pots for space efficiency; almost any material will do.

Three stages of fertilization will hasten the growing process and produce healthier vegetables. Mix all-purpose fertilizer and/or organic matter into the soil before you plant. Side dress another round of fertilizer six weeks after the seedlings show, then one more at 10 weeks. A balanced fertilizer is usually best, but some regions may require extra nitrogen or potassium. Do a soil test before planting to see what you need.

Unlike some vegetables, parsnips need 2-4 weeks of near-freezing temperatures for their best taste. This cold weather changes some of the starches to sugar. If properly overwintered with frost blankets and mulch, parsnips will flower and bear seeds in year two. When you finally harvest, though, pull all the roots from the ground or else parsnip plants can transform into unwanted weeds.

A round of pruning when the plants are about six inches tall will direct more resources to root development. Don’t remove more than one-third of the leaves or else you risk killing the plant. A little pruning on mature parsnips can delay them from going to seed.

Even with excellent care, parsnips take 100-120 days to reach their full size. To harvest them, loosen the soil with a digging fork, pull the root up by the top and cut the leaves off. Parsnips can be stored in the refrigerator at high humidity for up to four weeks or in a “cool cellar” for up to four months.