All-American' parsnip thickens early, in as little as 95 days! Parsnips have a long culinary history, are versatile and nutritious and are being added to the menus of many upscale and specialty restaurants. Their tender, white, carrot-like roots have a sweet and distinctive flavor that's delicious in soups and stews, mashed, stir-fried or roasted. The trick to growing the sweetest parsnips? Wait to harvest until after the first frost. Cold temperatures change the starch into sugar making them sweeter.