Growing Wild: A ‘How-To’ Guide for Avoiding Weed-Filled Wildflower Mixes

Wildflower mixes may contain noxious weeds. Here’s how to avoid invasive plants without sacrificing native beauty.

| January 2012

  • Dames Rocket
    One example of noxious weeds found by researchers in wildflower mixes is Dame’s Rocket.
    Richard Old, XID Services, Inc.,
  • Yellow Toadflax
    One example of noxious weeds found by researchers in wildflower mixes is Yellow Toadflax.
    L.L. Berry,

  • Dames Rocket
  • Yellow Toadflax

Wildflower mixes offer a quick and easy way to create vibrant meadows of colorful blooms — providing long-lasting beauty and a habitat for birds and butterflies. If you plant the wrong mix, though, you could end up with invasive or weedy plants as unintended guests in your garden or natural area.

One example: A wildflower mix was the source of an Oregon infestation of Paterson’s curse (Echium plantagineum), an exotic noxious weed native to the Mediterranean. This drought-tolerant plant is poisonous to grazing animals and can produce skin irritation and hay fever in humans.

University of Washington researchers shed light on the problem of weeds in wildflower mixes, examining 19 seed packets to see what lurked inside. Almost half contained seeds of plants considered noxious weeds in at least one U.S. state or Canadian province, such as dame’s rocket (Hesperis matronalis), oxeye daisy (Leucanthemum vulgare), Queen Anne’s lace (Daucus carota) and yellow toadflax (Linaria vulgaris).

In addition to noxious weeds, all the wildflower seed mixes in the study contained plants that can grow invasively under the right conditions. One example is common yarrow (Achillea millefolium), an aggressive grower that spreads through rhizomes and can crowd out desired species.

Even some of the ornamentals found in wildflower mixes can wreak havoc if they escape into the wild from their desired location. For example, bachelor’s buttons (Centaurea cyanus) is a prolifically blooming annual found in many wildflower mixes. Though well-behaved in most home gardens, bachelor’s buttons can aggressively out-compete native plants in a natural area. The same is true of the California poppy (Eschscholzia californica), another frequent favorite in mixed wildflower seed packets.

What can you do to keep noxious weeds and other invasive plants out of your wildflower garden and natural areas? First and foremost, be careful about what seeds you buy. Here are a few tips that can help:

Kevin Haendiges
4/13/2014 12:40:04 PM

The average gardener would not be familiar with the scientific names of plants, probably wouldn't know an invasive species from a hole in the ground, and seed mixes are cheaper than buying individual cultivars.

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