“Native plants give us a sense of where we are in this great land of ours. I want Texas to look like Texas and Vermont to look like Vermont,” said Lady Bird Johnson, who was the First Lady of the United States as the wife of President Lyndon B. Johnson.
Plants define the landscape. In California, besieged by the twin threats of drought and wildfire, the choice to grow native versus non-native plants is attracting more attention than ever before. What exactly are the merits of native compared to non-native plants, and how do gardeners make the best choice about what to grow in a home garden?
Native plants occur naturally in the area where they originally evolved. These plants have coevolved with wildlife, fungi, and microbes, and their interdependent relationships form the foundation of our native ecosystems, according “Native and Naturalized Plants for the Home Garden in Northern California.”
Every place has its own native plants, but California is spectacular in that most of the state is comprised of the “California Floristic Province,” a biodiversity hotspot that contains over 5,000 native plant species, more than 60% of which are endemic, meaning they are found nowhere else in the world.
With this stunning variety of native plants, you might expect to see them growing on every corner and offered for sale in every nursery and home improvement store, yet this is not the case. In fact, according to the California Academy of Sciences, 75% of the original native plant habitat in California has been lost , according to “Hotspot: California on the Edge.”
Since California natives are less commonly planted compared to non-native plants, you can become more familiar with them by visiting a local native plant garden such as the Butte County Master Gardeners Demonstration Garden at Patrick Ranch in Durham, the Alice B. Hecker Native Plant Garden at Chico Creek Nature Center, and the Native Plant Pollinator Garden at Gateway Science Museum in Chico.
But how do we know for sure that a plant really evolved in the local area? Botanical studies of the world’s flora have been ongoing for many years, and the historical record includes many specimens and drawings of plants that were originally brought to America by European explorers and settlers. In addition, paleobotanists have been able to compare fossil records with modern plants to accurately identify which plants are native to an area, according to “Native and Naturalized Plants for the Home Garden in Northern California.”
For gardeners, native plants have some important advantages. According to the California Native Plant Society, native plants are adapted to the local area and have natural defenses to local diseases and insects, minimizing the need for pesticides. Unfortunately, pesticides kill indiscriminately, so beneficial insects become collateral damage when pesticides are used. In contrast, native plants have built-in natural pest control, so that you can avoid the cost, mess and environmental damage involved in applying pesticides.
Another advantage to native plants is that once they are established, they normally need little watering beyond normal rainfall. With California experiencing an historic drought, native plants can help save significant amounts of water that would otherwise be soaked up by thirstier landscape plants. In general, native plants require less maintenance than non-native garden plants: less water, little or no fertilizer, less pruning, less of your time.
In addition, California native plants attract wildlife that use these plants as their natural habitat. For example, the many pollinators that flock to native plants can improve fruit set in your home orchard and yield in your vegetable garden. A variety of native insects and birds can reduce populations of mosquitos and plant-eating bugs. By using native plants, you support native wildlife and help preserve the balance of natural ecosystems, according to “Benefits of California Native Plants.”
As gardeners we have many choices about what to plant, even after allowing for what’s available locally and what we can afford. However, home gardeners may not realize that some of the non-native plants commonly available at garden centers and nurseries are invasive species or have the potential to become invasive; in other words, they are plants that threaten California’s natural ecosystems and cause damage to wildlife.
“California has the greatest natural botanical diversity of any state in the United States. In addition to nearly 5,000 native plant species, there are about 1,500 non-native species that have become established in the state. About 250 to 300 of these are weeds of agricultural crops, turf or gardens. The remaining 1,200 or so are naturalized plants of wildlands or disturbed non-crop areas, some of which are important invasive plants,” according to UC IPM Pest Notes: Invasive Plants.
Invasive plants can “disperse, establish and spread without human assistance,” and they cause disruption of natural ecosystems. The worst invasive species are called landscape transformers because they substantially alter the “character, condition, form and nature of the invaded habitat,” consuming resources needed for native plants to survive. When invasive plants replace native plants in the wild, wildlife that feed on the native plants suffer and may become endangered, according to UC IPM Pest Notes: Invasive Plants.”
Of the many species listed on the California Invasive Plant Council Inventory, 37% were accidentally introduced into the state, but “the remaining 63% were intentionally introduced as landscape, pond or indoor ornamentals, aquarium plants, soil stabilization species, animal forage species, or human food, fiber or medicine,” according to UC IPM Pest Notes: Invasive Plants.”
Home gardeners may be surprised to learn that commonly available plants such as periwinkle (vinca major), or butterfly bush (Buddleja davidii), are listed on the California Invasive Plant Council Inventory, as are sweet alyssum (Lobularia maritima), and gazania daisy (gazania linearis). Periwinkle, English ivy, Himalayan blackberry, and Chinese pistache, among others, have invaded our own beloved Bidwell Park. You may be dismayed to realize that you are growing invasive plants in your own garden! The University of California’s division of Agriculture and Natural Resources has information on how to determine whether a plant in your garden is safe to keep or should be removed, according to UC IPM Pest Notes: Invasive Plants.” The potential for a plant to spread from your garden to surrounding natural areas is a critical consideration in deciding whether to keep an invasive plant or destroy it.
When you shop for plants, “the key element is to know which horticultural plants are invasive in your area of the state. If a plant is listed as invasive in your region, it should be avoided for landscape use, especially for locations near natural areas. It may be safe to use in other regions, but sometimes the plant is not listed as invasive in an area merely because it has not yet become a presence,” according to UC IPM Pest Notes: Invasive Plants.”
For the five different regions of California, the PlantRight program identifies the most troublesome plants, as well as plants with the potential to become invasive, and suggests horticultural alternatives for them. For example, the PlantRight website highlights periwinkle (vinca major) as highly invasive in all five regions of California, and it suggests planting Bee’s Bliss sage (Salvia ‘Bee’s Bliss’) or yerba buena (Clinopodium douglasii) instead — both are native to California. But interestingly, not all of the alternatives they suggest are native plants.
Another plant on the watch list of the California Invasive Plant Council because of high potential risk is butterfly bush (Buddleja davidii); for alternatives, the website lists more than a dozen approved cultivars of this non-native plant.
Another fine resource for Butte County gardeners interested in planting responsibly is the list of Butte County All-Star Plants developed by the Master Gardeners and based on their experience at the Demonstration Garden at Patrick Ranch. These are plants that grow well in the local area. Almost all them are drought tolerant or require only moderate watering, and some are also California natives.
Gardeners interested in planting California native plants will appreciate the CalScape website where you can enter your address and search for plants that are native to your area. The search results are categorized in useful ways including low/very low water, butterfly hosts, very easy to grow, shade/part shade, annuals, perennials, and more. The information on each plant also details how the plant provides habitat for wildlife.
Clearly, home gardeners can support the health of natural ecosystems and conserve water in California by making wise choices about landscape plants. With non-native plants, make sure a plant is not invasive (or potentially invasive) before purchasing it, and be aware of its water requirements. Ultimately, California native plants are the best and most responsible choice, especially because of the ongoing drought and their diminishing natural habitat. The one drawback of native plants, perhaps, is that they can be harder to find; fortunately, the Butte County Master Gardeners program offers twice yearly plant sales featuring native plants at reasonable prices. One native plant at a time, home gardeners can help “California look like California” again in all its marvelous biodiversity.
The UC Master Gardeners of Butte County are part of the University of California Cooperative Extension system, serving our community in a variety of ways, including 4-H, farm advisers, and nutrition and physical activity programs. To learn more about UCCE Butte County Master Gardeners, and for help with gardening in our area, visit https://ucanr.edu/sites/bcmg/. If you have a gardening question or problem, call the hotline at 538-7201 or email email@example.com.