Oregano is a hardy perennial that may need winter protection to survive in the colder zone in northern Illinois. It may grow two feet tall with a rounded, sprawling spread of 18 inches. White or pinkish-purple flower spikelets appear in mid to late summer. The cultivar ‘Aureum’ has golden yellow leaves and develops into an 8–10 inch mound. Use oregano in Spanish, Italian and Mexican cooking.