How to kill off Zebra Grass and Valerian?

by Corrina
My mother in law and I have different ideas of plants. Un-killable she plants it. Invasive, I don't. I have inherited the garden filled with invasive's, most important now is Valerian and Zebra grass. We will get to the forget me not's and Evening Primrose soon. But I have tired digging this bugger up and it is a solid foot root if not more. My soil is clay. I live in Mid-Valley Oregon. I layered cardboard and let it die down for two years, it came back with a vengeance. Sprayed vinegar, baking powder even. It is close to my very shallow well, can't use the strong poisons. I am looking for more ideas. Thanks!
  4 answers
  • Janet Pizaro Janet Pizaro on Oct 14, 2015
    I would try a mixture of table salt with white vinegar and dish soap. Spray directly on the grasses them selves.
  • Kathy C Kathy C on Oct 14, 2015
    now I know Monsanto have a pact with the devil and all that, but honestly glyphosate is really good at murdering buggers, and the active ingredients break down upon contact with soil. A one off use won't hurt, it's repeated use in large quantities by agribusinesses that is suspect. The product I used to use was Clinic-Ace, now rebranded as Roseate -no doubt you have your own brands in Oregon. Use when the soil is moist and the plants at least 6 inches high and in vigorous growth and when you can expect 6 hours without rain. If you are worried about spray drift, roll it on with a paint roller. Anything vinegary might pickle but not kill the offending plants.
  • DianaB DianaB on Oct 14, 2015
    This site might help answer your question regarding glyphosate (Round Up, etc.) It is from the National Pesticide Information Center. Home remedies might also work but probably not at killing the roots which is what you are trying to achieve here. That being said, zebra grass is an ornamental grass and is rather pretty and don't know about its invasive qualities. Valerian being an herb and should look like this. You can Google this stuff and find lots of answers before trying to kill everything off. (guess the photo is not being posted) but the illustration is available on Wikipedia or any herb site.
  • Corrina Corrina on Oct 17, 2015
    Thanks for the info. The grass is more aggressive than ivy here. Roots go down over a foot and displace/overrun anything they tough. The valerian is pretty, some medicinal uses but I don't use it and its everywhere now actually competing with the teasel infest. They both take water from the other plants. I am so happy to have more research to read, thanks!