Some 'garden' plants are actually invasive species

"We're not talking about one hungry plant here, we're talking about world conquest." – Seymour, Little Shop of Horrors.

Most often we think of invasive plants as those that are not indigenous to a region. California claims the greatest amount of natural botanical diversity of any state in the U.S. We have nearly 5,000 native plant species. Over and above the native species, there about 1,300 established non-native species of which 200 to 300 are weeds. Some of these species were accidentally brought into the state; others were deliberately planted here for various purposes. Among these plants some are considered important invasive species. Once established, they are hard to get rid of or control. A prime example is the Kudzu experiment that has taken over the southern United States.

There can be undesirable consequences to the establishment of invasive species. Invasive weeds often are responsible for drastic changes to native ecosystems, such as interfering with natural habitat and food sources for animals, causing wildfires to be more frequent and intense, and lowering water tables by invasive trees that have deep rooting systems. Some plants even alter soil chemistry making it difficult for natives to survive.

These invasive species move out of their home ranges into new areas either by wind, birds or animals, or with human assistance that may be deliberate or accidental. This has been happening since the beginning of time. Humans have deliberately, and at times inadvertently, moved plant species from one region to another. With the development of high speed travel that doesn't take months to circumnavigate the globe, plants move with ease into areas where they were never before known. At times, plants that were once desirable and beneficial while under human control in gardens become a problem as they escape and start to colonize and breed in areas where they are not wanted. According to the California Invasive Plant Council, “The spread of invasive plants is one of the most significant threats to the native plant species and vegetation communities of the state, second only to habitat destruction.”

It's up to all of us to take some responsibility for reducing the problems caused by invasive species. One simple step is careful selection of garden plants by using species that are not likely to be invasive. The following plants are at the top of the list of invasive plants that should not be planted in California:

• Pampas grass (Cortaderia selloana)
  
  
• Green fountain grass (Pennisetum setaceum)

• Mexican feather grass (Stipa/Nassella tenuissima)

• Highway iceplant (Carpobrotus edulis)

• Periwinkle (Vinca Major)

• Yellow flag iris (Iris pseudacorus)

Instead of the above listed plants, try the alternatives shown on the Plant Right invasive plant website.

For a list with pictures of suggested non-invasive plants for California, take a look at Plant Right's better plant choices.

For further information about invasive plant species and what you can do to help, see the following websites:

Don't Plant a Pest! Central Valley

Don't Plant a Pest! California Invasive Plant Council (cal-ipc.org)

Invasive Plant Checklist for California Landscaping (pdf)

The 39 Most Invasive Plant Species in California

16 Invasive Species Sold at Garden Centers You Should Never Buy

Native Plants and Invasive Species

 (Originally written April 2021. Updated May 2024)