A recent article in the LA Times argued that California native plants should not be the only option for drought-tolerant landscaping. Missing from this perspective was a discussion of the severe threat that many non-native plants pose to California's unique and biodiverse ecosystems including reduced native plant establishment and increased fire risk. Additionally, we know that the nursery trade plays an important role in driving these invasions. For example, a recent study by researchers at the University of Massachusetts Amherst found that commercial nurseries are the primary introduction pathway for invasive plant species expected to increase their ranges under climate change.
Right now, consumers can find an array of known non-native, invasive plants readily available at their local nurseries, and there are many examples of invasive species that originally escaped from cultivation into wild areas throughout California including pampas grass (Cortaderia selloana) and English ivy (Hedera helix). Furthermore, it is difficult to predict which species will become invasive in the future. Even non-native species thought to be relatively low risk today could spread and cause harm in the future. Drought-tolerant plants from other regions with Mediterranean climates, which are highlighted in the Times' recent article, may pose the highest risk because the plants are already well suited for California's environment.
California is home to a huge diversity of beautiful and unique native plant species. In addition to providing many attractive and low maintenance options for drought-tolerant landscape design, our native California species have the added benefits of improving habitat for pollinators, birds, and other wildlife. In an increasingly urbanized California, native plant gardens could be an important strategy for conserving the State's biodiversity in the face of the ongoing extinction crisis.
We suggest that a greater emphasis on non-native species for landscaping is not necessary – the vast majority of species available for sale and commonly planted are indeed non-natives. Instead, we advocate for greater incorporation of native species in landscaping projects to aid in reducing water inputs while simultaneously promoting native biodiversity and limiting the spread of non-natives into California's wildlands. We encourage those looking to install drought-tolerant plants in their gardens to visit nurseries specializing in native species, and we hope that retail nurseries and landscapers will increase the availability of natives for consumers.