Tender is the artichoke. The 3-6' plants of this perennial produce 3-4" edibly tender flower heads in 18 months. With thick, fleshy scales and solid center, the flower heads should be harvested when they're young. Native to the Mediterranean, globe artichokes have been grown in the US since Colonial times. Thomas Jefferson raised them on his Virginia farm, Monticello, as early as 1767. Provided with a protective cover, the artichokes will successfully overwinter in colder areas.