• What is foreign grass?
Foreign grass is a wild form of grass that invades lawns and spoils the even and consistent color and texture. These grasses are often mistaken for “crabgrass”. In western Oregon it is very rare to see crabgrass. You’ll usually only find it in ornamental beds and then only during the hottest part of the summer, crabgrass is an annual that will die after one season of growth and can be controlled with the application of spring time “germination preventors”. In the Western Valleys of the northwest, our predominant foreign grasses are made up of a variety of perennial field grasses that do not die each winter but continue to slowly get larger and larger each year. The common seasonal (annual) grass in this area is called “poa” or “annual bluegrass”. This grass reseeds it’s self so quickly it appears to be a perennial. In time these grasses create an undesirable patch work for colors and textures throughout the lawn.
• Where does this come from?
Foreign grasses start from single seeds that often blow in just like broad leaf weeds. They originate in nearby fields, neighbors poorly maintained lawns and yes, even your own weedy flower beds. Foreign grasses can also germinate from soil activity such as the cultivation prior to planting a new seed lawn. Because these seeds can lay dormant for years until exposed to light the preparation of a new seed bed will often grow right along side of the desirable grass but not become obvious for several years. Installing new sod rather than seed greatly reduces this problem
• How can I get rid of them?
Broad leaf weeds are eliminated with products that leave the grass family plants unharmed. However, because foreign grass seeds are in the same family as desirable turf grass the products that eliminate them will also damage the grass that you want to keep. This makes things more complicated. No lawn can be totally free of foreign grasses but to keep them to a minimum and under control, follow these steps during the moist spring & fall months.
1. Spray the foreign grass patches with grass killer. Be sure not to walk through the spray while wet otherwise you will track it all over your lawn leaving footprints of dead grass.
2. After patches turn brown (10-15 days), rake out the thatch down to the soil level.
3. Using good quality seed (perennial rye grass) apply about two hand fulls of seed to each square foot of grass.
4. Lightly mulch the seed with peat moss using no more than a inch layer.
5. Lightly water the seed 2-3 times every day for 2-3 weeks unless it rains consistently. The seed should start to germinate in 10-14 days.
