Devil's grass is the common nickname for Bermuda grass (Cynodon dactylon). It earned this name because it spreads so fast that getting rid of it feels impossible. Once it takes hold in your yard or garden, you're in for a fight.
I learned how Bermuda grass invasive habits work the hard way. It crept from my neighbor's lawn into my flower beds over one summer. It sent runners under my edging, through the mulch, and around the roots of my plants. I pulled it out by hand for three weekends straight. Every small piece of root I left behind grew a new plant within days. The name "devil's grass" made sense to me after that losing battle.
The Bermuda grass invasive power comes from a dual spread system. Above ground, it sends out stems called stolons that run across the soil and root at every node. Below ground, rhizomes push through the dirt in all directions. They can travel several feet before sending up new shoots. Cut a stolon in half and both pieces grow into new plants. Dig up a rhizome and any small piece left behind restarts the invasion. This two-pronged attack lets it take over open ground faster than almost any other grass.
Bermuda grass thrives in heat that would kill your Kentucky bluegrass. It handles temperatures above 95°F (35°C) with no trouble at all. It grows strongest in USDA zones 7 through 10. Those are the same areas where bluegrass goes dormant or dies outright. Kentucky bluegrass prefers cool weather below 75°F (24°C) and can't handle long southern summers. The two grasses sit at opposite ends of the heat scale. If you grow bluegrass, you don't want Bermuda grass anywhere near your property. In my experience, even a small patch of Bermuda can take over a section of your yard in one hot summer.
The devil's grass vs bluegrass fight plays out most often in zones 6 and 7. Both grasses can survive there, but neither rules year-round. Bermuda grass takes over during hot summer months. Kentucky bluegrass fills in during spring and fall. You end up with a patchy mixed lawn that changes color with the seasons. The devil's grass vs bluegrass battle is the top frustration for transition zone homeowners.
You can manage Bermuda grass in your bluegrass lawn with barriers and targeted products. Install 6-inch deep plastic or metal edging along borders where Bermuda grass grows next door. This blocks most stolons and near-surface rhizomes from crossing into your yard. For patches already in your lawn, try herbicides with fluazifop. These products target Bermuda grass without hurting your Kentucky bluegrass. Apply them during summer when the Bermuda grass grows fast and your bluegrass rests.
Some homeowners in the transition zone choose to accept the mix and work with both grasses. Bermuda grass gives you green during summer heat. Kentucky bluegrass takes over in cooler months. Together they provide year-round green that neither grass delivers alone. Mow at 2 to 2.5 inches and fertilize in both spring and early fall to support this blend. It's not a perfect lawn, but it beats fighting a war against devil's grass that you can't win.
Read the full article: Kentucky Bluegrass Lawn Care Guide
