Turnips fall into two categories - winter and summer maturing. Winter maturing ones are generally rather bland and woody, and best avoided. Summer maturing turnips are a different matter altogether, they're small sweet and packed with flavour. I generally harvest mine when they're about 2in wide so they can be added to stews or roasted/braised whole. Served up, they look and taste amazing. They can be harvested just 8 weeks from sowing.