Converting Non-Native Roadsides to Native

Occasionally a landowner will contact the county IRVM program to request a native planting adjacent to his/her property. If the site is conducive to a successful native planting, some counties accommodate these requests. Converting non-native vegetation to native requires eliminating the existing vegetation, usually by application of glyphosate. Cool-season grasses such as brome, fescue and bluegrass can be persistent and might require more than one application.

  • Kill existing vegetation with a 2% solution of glyphosate in April or May.
  • If thistles and other broadleaves are present, apply a Transline/Telar mix the fall prior to glyphosate in the spring.
  • Apply the herbicide when existing vegetation is green and growing but no more than 12 in. tall.
  • If there is still green grass after ten days, apply the herbicide a second time.
  • Consider keeping the top 4 ft. of the foreslope unsprayed, leaving it stabilized with mowable, cool-season grasses.
  • A native grass drill is most effective for planting into the dead stubble, disturbing the dead turf as little as possible while getting seed in direct contact with soil.
  • Keep the entire planting mowed during the first growing season because weeds will likely be released once the existing cover has been destroyed.
  • In subsequent years, spot-spray weeds as they appear.

Establishment mowing

During the first growing season, native seedlings remain small and can suffer losses due to competition by tall, thick weeds.

  • Mow the planting three or four times during the first growing season.
  • Don’t wait until the weeds are too tall.
  • A mowing height of 4 in. is good but to avoid scalping, 8 in. is better.

Evaluating new plantings

First-year native seedlings are small, making them hard to find and even harder to identify. As a result, people often worry or assume the planting is a failure.

  • If the success of a seeding is being challenged, hire a botanist to look for seedlings.
  • Unless a planting is washed out by heavy rains, allow two full growing seasons before giving up and starting over.