National Invasive Species Week (NISW) happens every year to raise awareness about the growing problem of invasive plants and animals in the United States. For 2025, we're putting special attention on how invasive plants affect California's natural areas, farms, and communities—and the steps we can all take to stop them from spreading. According to UC Davis, California currently has more than 1,700 invasive species that threaten our state.
Invasive plants may seem harmless at first, but their rapid growth can disrupt ecosystems, damage property, and cost millions in control efforts. From taking over native habitats to increasing wildfire risks, these plants create long-term problems that affect both nature and people.
The good news? We can all play a role in stopping them! In this blog, we'll break down what makes a plant invasive, why they're a problem, and simple steps you can take to help protect California's environment.
What Makes a Plant Invasive?
Have you ever noticed a plant taking over your yard, a park, or even an entire hillside? Some plants grow so aggressively that they push out everything else around them. These are called invasive plants, and they can cause serious problems for nature, our economy, and even our daily lives.
Invasive plants come from other regions and don't have the natural checks and balances that keep them under control in their home environments. This lets them spread quickly and take over.
Most invasive plants share some key traits:
- Fast Growers – They produce lots of seeds and spread rapidly.
- Easy to Spread – Their seeds travel by wind, water, animals, or even hitch a ride on your shoes.
- Tough and Adaptable – They can grow in many different environments and soil types.
- No Natural Enemies – Local animals, insects, and diseases often don't affect them, so they grow unchecked.
How Do They Harm the Environment?
Invasive plants don't just grow fast—they change entire ecosystems. Here's how:
- They Crowd Out Native Plants – Native species struggle to survive when invasive plants take up space, sunlight, and nutrients.
- They Mess With Fire Patterns – Some invasive grasses make wildfires happen more often and burn hotter, which can damage natural landscapes.
- They Alter Habitats – Thick growth can make it harder for native animals to find food and shelter.
The Cost of Invasive Plants
The damage doesn't stop with nature—invasive plants can also hit our wallets:
- Farmers Lose Crops – Invasive weeds take nutrients from crops, lowering harvests and increasing costs.
- Property Damage – Some plants, like Japanese knotweed, grow through pavement and foundations, causing expensive repairs.
- Expensive to Control – Removing invasive plants takes a lot of time, effort, and money.
What Can We Do?
The good news is that we can all help stop invasive plants! Here's how:
- Catch Them Early – If you see a new invasive plant in your area, report it before it spreads.
- Choose Native Plants – Avoid planting invasive species in your yard and choose native alternatives instead.
- Follow the Rules – Some invasive plants are banned from sale or transport—make sure you know the laws in your area.
Best Places to Report Invasive Plants in California
- California Department of Food and Agriculture Pest Hotline 1-800-491-1899- Report invasive species (including plants) directly to the State of California over the phone or online.
- Local County Agricultural Commissioner-Each agricultural commissioner is charged with the protection of California agriculture, the protection of the environment as well as protection of the public's health and safety
- UC Master Gardener- Your local UC Master Gardener office can provide guidance on invasive species and direct you to the right reporting system , they can even help identify pests and plants if you aren't sure what they are.
- Calflora, Observer Pro- A citizen science platform where you can submit observations of invasive plants, including photos and location details.
- California Invasive Plant Council (Cal-IPC)- A great resource for identifying and reporting invasive plant sightings.
- INaturalist- An easy-to-use app where you can upload photos of plants, and experts help confirm their identity. Data is shared with scientists and conservation groups.
- Early Detection & Distribution Mapping System (EDDMapS)- A national invasive species mapping tool used for early detection and tracking.
By staying informed and taking action, we can protect our local ecosystems and keep invasive plants from taking over. Every little effort counts!