Zyosia Grass

Question: My front lawn has had Zoysia for over 40 years. The last couple of years there is another wide blade grass taking over the Zoysia. Can you tell me  what type of grass this is and what can I do to get the Zoysia back?

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied April 24, 2023, 12:04 PM EDT
response: We are checking with one of our turf experts about this situation since zoysia usually doesn't have many weed incursions due to its "self-repair" ability to fill-in gaps and thin spots. Zoysia needs regular dethatching to keep it vigorous, even though it doesn't need annual overseeding the way a fescue lawn would; has the lawn been dethatched in recent years?  Grass ID requires the examination of fine details that can be hard to see in photos. We think we see a structure (called auricles) on the wide-bladed grass in the first photo that resembles those of Quackgrass. You can use the information on the linked page to see if it appears to match that particular grassy weed. Has your zoysia started to green-up already? We weren't certain if the other photos were showing dead brown grassy weeds in zoysia that has resumed growth, or green cool-season grassy weeds in still-dormant zoysia.  Other measures to keep the zoysia as vigorous as possible include keeping mower blades sharpened once or twice a year (the blades used on this lawn appear to be very dull, as evidenced by the quite ragged, desiccated, and torn leaf blade tips), mowing at the recommended height (which tends to be lower than for fescue overall), and periodic laboratory soil testing to make sure any nutrient deficiencies (if applicable) are addressed with fertilization. We have a few web pages mentioning zoysia care (intermingled with the majority of the information focused on fescue) among our Lawn Care and Maintenance resources that may be of help.  Miri

responder: The Question Asker Replied April 25, 2023, 9:07 AM EDT
response: Hi Miri, Thanks for responding to my problem. To answer your questions: I have never had it dethatched. The brown patches are Zoysia that has not greened up as yet. I do have a new blade that I will put on the next time I mow. I do tend to mow a little high. I have a lawn company fertilize on a regular basis. I never have them over seed the Zoysia, only the Fescue on the side and back of my house. Is there someone that can come out and look at the lawn and tell me what is going on? Thanks, Joe

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied April 26, 2023, 11:34 AM EDT
response: Hello Joe,  Thank you for the additional information. Zoysia definitely should be dethatched periodically (perhaps every 3-4 years depending on how rapidly the thatch layer builds up). The lack of dethatching could be one reason why the long-established zoysia part of the lawn is struggling to remain vigorous. After some consultation, we think the invading green grasses are primarily tall fescue, likely moving in from other parts of the yard or from nearby properties. This complicates lawn care since cool-season turf and warm-season turf has different maintenance regimes. You could overseed with fescue this autumn to make it look more uniform, though usually we discourage mixing the two given the inability to give both turf types their ideal care for best health. Otherwise, the only way to get rid of the undesired non-zoysia grasses is to physically remove all of the affected turf and start a new lawn over or to chemically remove it with herbicide while the zoysia is still dormant (as a foliar spray of herbicide won't hurt it that time of year).  Miri

responder: The Question Asker Replied November 15, 2023, 9:30 AM EST
response: What is the optimal ph and other soil concentration for Zoysia grass eg…P,k,Ca Mg? Thanks, Joe

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied November 15, 2023, 10:16 AM EST
response: Hello Joe,  A pH range of 6.0 to 6.8 is ideal for turfgrass (fescue and zoysia). As per our Lime and Lawns page, if the pH falls below 5.5, then the vigor of the grass might be compromised. A laboratory soil test is the best way to assess both pH and nutrient levels. There are no specific soil concentrations of P, K, Ca, and Mg that need to be met; rather, if a soil test shows a particular deficiency (usually flagged as "low" on the test results), then it could be supplemented with fertilizer as needed. Any results that indicate "excessive" levels do not need to be reduced; while "excessive" sounds detrimental, all it really means is that adding more of that particular nutrient will not benefit the grass and may contribute to nutrient runoff pollution in stormwater since the grass can only make use of a finite amount of nutrients.  Miri

responder: The Question Asker Replied November 15, 2023, 10:29 AM EST
response: Thanks On Wed, Nov 15, 2023, 10:16 AM Ask Extension <<personal data hidden>> wrote: