When selecting any root vehetables in the store, look for heavy, firm - not spongy roots. Turnips & rutabagas should be fairly clean and free of decay. If there is the slightest indication of immature leaves growing from the top, then the root is old and "re-sprouting." This will result in a tough woody root. Turnips with long green leaves and small roots are fresh picked and both the turnip and the greens are eaten.
Store at home in the refrigerator for a few days. Keep them hydrated for maximum freshness.