By Greg Rubin, CNPS-San Diego Garden Native Committee member
Article reposted from California Native Plant Society Blog
Few things evoke magical memories like spring wildflowers. Whether it is a desire to recapture a serendipitous discovery of a color-laden flower field from our past, or simply re-living that scene from the “Wizard of Oz”, nothing stirs our passion for nature like a beautiful field of flowers. California was once celebrated for its annual floral shows; unfortunately, these delightful events are becoming a thing of the past. The great Kate Sessions lamented that wildflowers were disappearing from San Diego’s foothills by the early 1900s. Even her attempts to include wildflower displays at Balboa Park repeatedly failed. Why?
The answer is that European settlement in California altered our delicate ecology so profoundly that it was lost at all levels. Nothing is quite so fragile as a wildflower meadow. These annuals serve as pioneers that help re-establish ecology should a disturbance wipe out climax shrubs and trees. Being so low in lignin, they disappear after dying, returning all of their nutrients back to the ecology. Additionally, they fill holes not occupied by shrubby plants, and persist in places inhospitable to anything with deep roots, such as in the shallow soils of true native grasslands. What the Europeans brought were non-native weeds: competitive plants unhindered by native bio-controls while putting all of their life energy into reproducing themselves. These non-native seed banks now reach 10-100,000 dormant seeds per cubic foot! The wildflowers never stood a chance.
Fortunately, knowledge is the best tool, and we have ways to turn back the clock. Eliminating weeds is foremost. It is usually not sufficient to clear a space and drop seed, as Ms. Sessions learned. Instead, the seed bank must be addressed, either through repeated watering and killing of emerged weeds, or the use of chemicals called pre-emergents that kill seed in the soil when watered in. This must be done months in advance of planting. Solarization with clear plastic can also be used, but the effect is usually temporary. After treatment, seeds can be spread and either gently raked in or covered lightly in decomposed granite (this avoids disturbance and deters birds). Wildflower seeds can be purchased at most garden centers and online; however, be sure that the word “NATIVE” is somewhere in the title, and that the species are native to your locale, or you will end up with a mix of weedy introduced flowers, the worst being Alyssum. (ED note: You can check the local appropriateness of your chosen seed mix ingredients by entering your address in CNPS’s Calscape app, available at calscape.org or on CNPS’s homepage.) Common native mixes include California Poppies, Lupines, Goldfields, Desert Bluebells, Gilia, Baby Blue Eyes, Tidy Tips, and Farewell-to-Spring. You can add Owls Clover, Five Spot, and Thistle Sage if available. Keep the plot lightly moist until germination, continue watering twice a week if rainfall is lacking, and CONTROL WEEDS! The outcome will be thrilling!
CNPS Member Greg Rubin is the founder and owner of California’s Own Landscape Design, Inc. (www.calown.com) and a popular speaker. A specialist in the use of native plants in the landscape, he is responsible for over 700 native landscapes in San Diego County and co-authored (with Lucy Warren) two books on native landscaping: The California Native Landscape: the Homeowner’s Design Guide to Restoring its Beauty and Balance and The Drought Defying California Garden: 230 Native Plants for a Lush, Low-water Landscape, both on Timber Press.