Wildflower Mixes

Local Streams

Two-thirds of listed endangered species are threatened by non-native plants. Non-native species also have an economic impact; in the US, $185 billion per year is spent combating invasive species.

The Wild Side of Wildflower Mixes

Over the years, agencies have routinely used wildflower seed mixes to beautify roads and highways. These seed packets also became popular with gardeners wanting to add low maintenance, water-wise color and “butterfly habitat” to their gardens. Over time, however, more and more plants such as orange hawkweed, bachelor button and butterfly bush started springing up in places that were not seeded. This attracted the attention of scientists and ecologists, who became concerned with the impacts these plants may be having to local streams and ecosystems.

Scientists found that these plants, once considered harmless, were spreading like wildfire and “naturalizing” woodlands, prairies, streamsides and wetlands. Naturalizing is when a plant (or animal) comes from another region and becomes1 successfully established in its new environment. Many of these plants fit the definition of a noxious weed or invasive species.

Why the concern?

Nonnative species (both plants and animals) can have a devastating impact to the lands and water that native plant and animals depend on for survival. The end result is the destruction of wildlife habitat and forage that impacts native species. Two-thirds of listed endangered species are threatened by non-native plants. Non-native species also have an economic impact; in the US, $185 billion per year is spent combating invasive species. In Oregon, Scotch broom alone has a $46 million dollar per year impact. As non-native wildflowers and other plant species spread, the loss of habitat and costs to control these species continue to escalate.

Wildflower seed mixes.

University of Washington studies showed that many commercial wildflower seed mixes have noxious weeds and/or invasive species included in the mix. How do they get into the seed mix? Many of the seeds are intentionally put into the mix as they are easy to grow and reproduce abundantly and quickly. Others plants get included into the seed mix though contamination, as they are harvested.

Unfortunately, the labels on many wildflower packets do not include a seed mix list or have a list that is inaccurate, making it nearly impossible for conscientious gardeners to avoid invasive plants. For this reason, researchers at the UW stated that they could not recommend using any wildflower seed mixes.

What you can do:

  • Do not plant commercially-packaged wildflower mixes.
  • Plant native species.
  • Consult with your local Noxious Weed Control Agency for alternative options (co.thurston.wa.us)
  • Utilize local plant guides such as Common Sense Gardening Guides: www.co.thurston.wa.us/health/ehcsg/guides.html
  • Never place invasive plants/noxious weeds in the compost! Consult your local Noxious Weed Control Agency at the address above to learn the best way to remove and dispose of invasive plants.

In Washington State, noxious weeds are defined as “a plant that, when established, is harmful or destructive or difficult to control using cultural or chemical practices”.

Invasive species are non-native (or alien) plants, animals or pathogens whose introduction causes, or is likely to cause, economic or environmental harm or harm to human health. These invaders are successful because they can spread unchecked due to the lack of natural competitors or predators. Without these natural checks and balances, they are able to reproduce rapidly and out-compete native species.