Invasive grass with underground 'runner' root spreading.
The grass in consideration appeared a few years ago in one flower bed. It has broad leaves that break through the soil every few inches, 6" t0 12", i'm guessing. I have dug down with a garden tool and found them attached to under-ground runners that can be unearthed for several feet at times before they break off. Also I have found sharp pointed side runner starts that often break off when extracting the main runner which I assume are just adding to the network of this plant that is taking over this particular area. My question is how to deal with this unwanted grass on a more effective and permanent manner. I haven't seen it entering the adjacent lawn area yet but maybe because the mower keeps it cut off. Short of removing all the ornamental plantings and doing deep excavation, is there a practical known way of dealing with this plant? I don't know if it is killed by 'Roundup' type herbicide but it would be hard to apply it without also killing other vulnerable plants near by. Carl Bankes I tried to send a picture but couldn't make the transfer. Apr. 9, 17.
Washington County Oregon
Just to let you know that I'm the most recent person to be assigned your question. Seems that it has passed through a number of (frustrated) hands. I'll return after I consult with a colleague or two.
Sorry to hear of your travails with quackgrass, a weedy grass that spreads via tough, nearly wiry, underground rhizomes. “If the infestation is not severe, regular hoeing or pulling of the quackgrass can eliminate the plant. . . . remove the shoots before the 4th leaf develops as this is the point at which nutrients are transported back replenish the rhizomes.” (https://weedecology.css.cornell.edu/weed/weed.php?id=12) By doing so, you will gradually starve the perennial root system.
Yes, it will require prolonged and persistent battle. But you can win as long as you don’t allow the grass any growing time past that 4th leaf. You could also use a paint-on application at the 4-leaf stage. But, to be frank, I think it would be easier to make the rounds every week, or so, to yank out any greenery you see.
You can win if you are persistent!
If you leave for vacation, either enlist a friend or hire a teen to continue the effort while you are gone.