The dainty yellows, purples or reds of wallflowers (Erysimum spp.) brighten rock gardens or native prairies in late spring and early summer -- some bloom nearly year-round treated as annuals in warm climates. Native varieties are water-savers and some varieties are fire-resistant. It's a big family with plants native to Europe, Asia and North America. Your wallflowers might be annuals, biennials or short-lived perennials. Not all types should be cut back at the same time.
Biennial and Perennial Maintenance
Coastal wallflower (Erysimum capitatum) is perennial in U.S. Department of Agriculture plant hardiness zones 3 through 7 -- and the biennial form (Erysimum asperum) has a similar range. These native varieties will self-seed, a must for plants that only live for two or three years. English, or Aegean, wallflower (Erysimum cheiri) is a colorful non-native biennial, that grows in USDA zones 3 through 9. Allow perennials and biennials to bloom and set seed before cutting them back in late summer or fall when the seed pods dry and shatter. Collect seeds before their pods shatter to plant wallflowers elsewhere.
The Annual Wallflower
Annual wallflowers such as Alpine wallflower (Erysimum linifolium) -- and others treated as annuals -- complete their life cycle in one year. Pinching in early spring before flower buds begin forming forces the plant to bush out, increasing bloom. Cut annual wallflowers early to use in arrangements -- they will continue to bloom until they can set seed -- or late summer heat causes them to fade. When flowers stop, cut the plant back or pull it -- it's finished.
- Michigan State University Extension: Wildfire-Resistant Landscape Plants for Michigan
- Missouri Botanical Garden: Erysimum Capitatum
- Colorado State University Extension: Western Wallflower – Erysimum Asperum
- University of Massachusetts Extension: Erysimum Cheiranthoides
- Clemson Cooperative Extension: Growing Annuals
- Sunset: Erysimum
- Photo Credit mtreasure/iStock/Getty Images