Turnips are a versatile crop. Like beets, they can be grown for greens or for the bulb. They grow fairly quickly, maturing in about 2 months, so you can get more than one harvest in a season. However the bulbs form best in cool weather, around 60 F., so early spring and fall crops are favored. We are most familiar with the white and purple tennis ball-sized turnips commonly sold, but there is a good deal of variety, including small, tender radish-sized turnips. Turnips are biennials grown as an annual crop. They may go to seed in their first year, if they were planted early in the spring. Get more instructions on taking care and harvesting here.