Walla Walla Onion-This near legendary onion is noted for its mildness. In the Northwest it is planted in the fall, over-wintered, and harvested the following spring. It will produce an acceptably mild crop from a spring planting in areas with more severe winters. You can also try to protect it over the winter with a light mulch. We've had mixed results with this method. Worth some experimentation if you crave a mild onion. Long day.