In areas of the U.S. where winters are mild, Siberian Wallflower (Erysimum cheiri), (formerly Cheiranthus cheiri), is an early flowering favorite in the late winter garden. The species hails from Southern Europe (USDA hardiness zones 7-9). Many books list them as biennials and a few as “tempermental perennials”. Wallflower is a woody-based herbaceous perennial subshrub in the mustard […]