gardening - noxious weeds

A bee gathers pollen on a Scotch thistle weed in the Wenas Valley.

The Yakima County Noxious Weed Board wishes you a weed-free happy New Year and new decade.

The holidays are wrapped, guests and travelers have returned home, the weather is still cold, and … this is the time when gardeners start looking ahead. We’ll soon be receiving seed, bulb and plant catalogs from across the country, and many of us start getting spring fever. We start daydreaming about getting outside and trying some plants we’ve never grown before.

If you find yourself looking at lovely new and exotic beauties that might grow in our climate zone, STOP! You need to do a little research first. Ask a few questions before you place that seed, plant or root order:

1. Is it OK to plant that species and variety in Washington state? Check the Washington State Noxious Weed Control Board website ( or call the local office.

2. Will it take over my landscape in a few years? After it is established, how wide and tall will it get? Is it a clumper, or does it spread vigorously by rhizomatous roots? Is it a rampant re-seeder?

3. How easy or difficult is this plant to control once it is established? Will I need a backhoe to remove it?

4. Is it toxic? Will it affect children, pets or livestock if they come in contact with it or eat it?

Nearly half of the plants on the Noxious Weed List are escaped ornamentals. Remember that Central Washington is an irrigated shrub steppe-grassland mix. Long, warm summers and irrigation make it suitable for very successful invaders! Tropical and subtropical plants that were once believed incapable of overwintering here have proven to be hardy without any added winter protection.

Certain species have invaded or escaped into unwanted locations throughout our Valley, adversely affecting rangelands, riparian zones, pastures and crops. Plants such as “Hardy Pampas Grass,” also known as Ravenna grass, have escaped and started taking over irrigated and riparian areas in Eastern Washington. Aquarium plants, such as Parrot Feather, once considered to be tropical, have been found in streams and ponds along the Yakima River.

The list of escaped ornamental plants is extensive. The point is, home gardeners can help prevent further escapes by knowing ahead of time what plants are unsuitable for our gardens. Many of these thugs have multiple common names, and sometimes slip through the cracks of nursery inspections and “do not sell” lists. However, there are resources available to help determine whether we should buy and plant a new species.

Noxious weed boards and Master Gardeners work together to make information available to landowners and advise on what plants should be avoided.

There are photo ID cards of the plants we should avoid. Additionally, the “Eastern Washington Garden Wise” booklet (available online through the Noxious Weed Control Board at has some alternative plants to use in their place. Plant these recommended alternatives to pretty but noxious weeds:

Japanese, Giant, Himalayan and Bohemian Knotweeds (False Bamboo): Replace with Lilac, Goat’s Beard, False Solomon’s Seal or Red Osier Dogwood.

Ravenna Grass (Hardy Pampas Grass): Replace with Basin Wild Rye, Shenandoah Switch Grass or Karl Foerster Feather Reed Grass.

Basket flower/Bighead Knapweed: Replace with Giant Yellow Star Scabiosa, Black-eyed Susan or Blanket Flower.

Remember, nearly half of the plants listed on the Noxious Weed List are escaped ornamentals. If a plant is easy to establish, self-seeds and requires little effort or maintenance to grow, it has great potential to become invasive. We want you to enjoy the plants you spend money on and physical labor putting into your landscape. Make sure they aren’t plants that the Noxious Weed Control Board inspectors will ask you to remove.

If you have any questions or concerns, contact the Yakima County Noxious Weed Board at 509-574-2180 or email

Susan Bird is maintenance and outreach specialist for the Yakima County Noxious Weed Board.

WSU Extension Master Gardener Program is an organization of trained volunteers dedicated to horticulture and community service. The Master Gardener Walk-In Diagnostic Clinic operates from 9 a.m. to noon and 1-4 p.m. Mondays, Wednesdays and Fridays. Direct questions about gardening, landscaping or this program to the Master Gardener Clinic at 509-574-1604, or leave samples for identification at the WSU Extension office. Leave a message with your name, phone number, email address and the nature of your problem or question. You can also email your questions to and include pictures if you have them. A member of the Master Gardener Clinic team will check voicemails and emails, and reply as soon as possible. The WSU Extension office is at 2403 S. 18th St., Suite 100, in Union Gap. Call 509-574-1600. New volunteers are welcome.