A:   Turnips should be planted in late July through early August for best results. This gives them 80 to 90 days of growing season before temperatures below 20 degrees stop further growth. Seeding rates usually are between 3 and 5 lbs per acre and seeds must be placed no deeper than one-eigth inch deep. Many fields benefit from 20 to 40 lbs phosphorus and 40 lbs nitrogen, especially if moisture is sufficient to grow an abundant crop.