It pained me the day I purposefully pulled up my favorite spring-blooming perennial. This plant was in the yard when I moved in, and I was delighted to have such a reliable performer. I loved its tall stems, its showy purple flowers and the way it seeded itself so easily.

Dames's Rocket

Reliable and beautiful, dame’s rocket was my favorite spring flower in my garden. Then to my surprise, I learned that it’s actually an invasive ornamental!

Photo Credit: Jodi Torpey

Dames's Rocket flower

Dame’s rocket can be mistaken for taller varieties of phlox. However, dame’s rocket flowers have only four petals, and its lance-shaped leaves grow alternately along the stems.

Photo Credit: Jodi Torpey

English Ivy

The National Wildlife Federation lists English ivy as one of the most harmful invasive plant species in the US.

Photo Credit: Jodi Torpey

That’s why I was surprised to learn that dame’s rocket (Hesperis matronalis) is actually considered a noxious weed in my state – and in many others, too. All of the characteristics that made my favorite flower perfect for my garden just happened to be the same characteristics of a noxious weed.

Many invasive plants started out as non-native ornamentals planted in backyard gardens. But once they escaped into native plant communities, they started to take over. And when invasive plants get a foothold on an area, they can cause irreparable agricultural or environmental damage. Because of their ability to spread quickly, invasive ornamentals can choke out native plants and ultimately change an entire ecosystem. Take for example the non-native plant saltcedar (Tamarix). In Colorado’s wetlands and riparian areas, this thirsty invasive is pushing out the native trees that provide bird and wildlife habitat.

Because invasive plants are opportunistic, climate changes related to global warming help them spread into new areas. That’s one reason the National Wildlife Federation is asking gardeners to help reduce the threat of invasive species expansion. Some of the most harmful invasive plants to be aware of in the US are purple loosestrife (Lythrum salicaria) and Japanese honeysuckle (Lonicera japonica). And plants as innocent-looking as English ivy (Hedera helix) are nearly impossible to eradicate once they escape from cultivation in some regions of the country.

But there are things you can do to help the situation and prevent further spread of invasive plant species:

  1. Do some research. Familiarize yourself with your state’s invasive plants. Learn to recognize invasive ornamentals in their different stages of development.
  2. Take a plant inventory. Review what’s growing in your garden and make sure you know what each plant is. Compare any unknown plants to your state’s invasive-weed list or ask your local Cooperative Extension Office to help identify it.
  3. Take action. Remove invasive ornamentals by hand-pulling or chemical means. Dispose of the plants by double-bagging them for trash removal. Replant the area with native ornamentals.
  4. Watch for their return. Some invasives reseed and grow in the same season. Others may not appear until the following growing season. Whenever you see them, be sure to remove them, double-bag them and dispose of them as above.
  5. Read labels. Before planting any wildflower or other seed mixes, read the label to make sure none of the plants are on the noxious-weed list. Avoid planting anything when the contents aren’t clearly described or if there are some prohibited ornamentals listed. And make sure anything you order through a catalog or Website won’t be a problem in your state.
  6. Take stock of the neighborhood. Keep a watchful eye to make sure invasive plants haven’t escaped into nearby properties, wetlands or open spaces. Notify the appropriate state or county weed-management agency if you see plants that need to be eradicated.
  7. Spread the word. Help other gardeners understand which ornamentals can cause harm to the environment and how to properly get rid of them if they have an invasive.

It would have been easy for me to ignore the potential problem my dame’s rocket presented. However, I didn’t want to shirk my responsibility to the environment or hide from the problem like one gardener I met: She refused to believe the beautiful purple loosestrife growing in her yard could ever become an issue for the neighborhood around her. She insisted her tall fence could keep wind, rain, birds and other small animals from dispersing the seeds. If her fence works, it’ll be magic!