Ask Mr. Smarty Plants

Welcome to our world! We cannot tell you how many questions we get from people in North America and even around the world wanting to know how to get out of bad situations, usually situations for which they are not to blame. Many of these questions are about planting or not planting plants that are invasive, not native to North America or to the area in which they live and then they suffer the consequences. The Lady Bird Johnson Wildflower Center, home of Mr. Smarty Plants, is comitted to the growth, propagation and protection of plants native not only to North America but to the area in which those plants are being grown; in your case, Washington County, PA, on the west central border with Ohio. In other words, two native plants might be native to North America; one native to Pennsylvania might fry in the Texas climate and one native to Texas would no doubt freeze to death in Pennsylvania. This can have to do with the climate, rainfall and soils being incompatible with some plants and totally hospitable to others.

All this, however, makes little difference in your situation, because Zoysiagrass (as it is often called) is not native to North America at all, but rather to southeast Asia, China and Japan. Because it is not native to North America, we have nothing about it in our Native Plant Database, and if you go into a nursery to ask about it, they will either sing its praises or recommend a broad-spectrum herbicide, which you already know is a bad mistake. To try to find you some more impartial information, we went to the University of Rhode Island Landscape and Horticulture Program and found this article on Zoysiagrass. Continue reading and scrolling down that page to read the portions on 'Advantages" and "Disadvantages"and further down to "Elimination of Zoysiagrass." 

So, we are not making much progress with your immediate problem. We tried to find some better information and found this article from Gardening Know How Removing Zoysia Grass: How to Contain Zoysia Grass. Beyond that, we have one last suggestion which we have repeatd several times to others struggling with the lawn issue.

It's called 'lose the lawn." To help you know what page we are on in terms of lawn grasses, please read this recent article from the New York Times "Lose the Lawn". From a recent answer on impossible problems with lawns:

More and more, we are encouraging gardeners to move away from grass or formal lawn,  Here is a previous Mr. Smarty Plants answer that might point you in some good directions. From another Mr. Smarty Plants answer:

We would suggest you perhaps embark on a process of xeriscaping. From eartheasy, here is an excellent article on Xeriscape. Obviously, you do not have to do every single thing suggested for xeriscaping, but you can start small and work your way up. We had one letter from a homeowner this week that said they were so over grass, and we feel that may be a very good idea.

We fully realize that you first have to get rid of the zoysiagrass, maybe in smaller, manageable portions, perhaps using a sod cutter as suggested in one of the above references. We truly wish we had a magic formula to instantly make the grass disappear but, short of a time machine to go back and not plant the stuff, we have nothing.