Direct sow outdoors in early spring, 2-3 weeks before last frost, and anytime after (until mid-late summer). Space seeds about an inch apart in rows 12 inches apart. Thin sprouts to 2 inches apart and then, once they reach 3-4 inches tall, thin to 4-6 inches apart. Keep soil moist and cover with light-weight row cover to protect from flea beetle damage. Turnips prefer rich, fertile, well-drained soil and plenty of water. Harvest when roots are young, about 3-4 inches in diameter. Eat immediately, or cut the leaves off and store the roots.