JoAnne Skelly
Recently I was in a box store’s garden department and noticed two products claiming to solve common landscape challenges. One of these was a lawn product “powered by microbes” that reported it improved drainage, water and root penetration and airflow by aerating and dethatching the lawn without the need for machines.
When grass roots can grow more deeply into the soil, the lawn should be more drought-tolerant. This product is not a pesticide but relies on a mix of beneficial microorganisms to decompose the thatch buildup and to convert that material into nutrients for the lawn. It also helps loosen clay, reducing compaction. The label states that it is safe for pets and children.
It can be applied with a hose-end sprayer, a portable sprayer or purchased in a spray applicator bottle. The company recommends using it in the spring after the lawn is actively growing and in the fall before the lawn goes dormant. You should see lawn improvement within four to six weeks of initial application.
The advantages of microorganisms in building good soil are well documented. They do decompose organic material, which then become nutrients in the soil. Whether or not microorganisms are effective enough to solve all thatch and aeration problems, I don’t know. I expect it would depend on the depth of the thatch and how compacted the soil is.
Another product says it “kills many common weeds like dandelion, clover and thistle” but not grass and that it is derived from iron chelate rather than traditional chemicals found in most broadleaf weed killers. It also works on moss and algae in lawns. The label states that weeds will start to die within hours of application. There may be a temporary darkening of grass blades. It also can be used for controlling weeds before they emerge. Even though its active ingredient is iron, it is still a pesticide and as such it can have environmental impacts if used improperly. It shouldn’t be applied to a drought-stressed lawn. Water the grass thoroughly before use. Rinse the product off any desirable plants, hardscape surfaces, or clothes because iron does stain.
Iron chelate has long been used to green up a yellow lawn. I hadn’t read about it as an herbicide before. Supposedly the mode of action is that broadleaf weeds absorb the iron chelate more readily and in larger quantities than grass. This damages cells in the broadleaf plants and leads to death when coverage is thorough. Iron chelate is in the lowest Environmental Protection Agency’s toxicity category.
Since the university doesn’t endorse products, if you want to find them, go to a local box store, and read product labels.
JoAnne Skelly is Associate Professor & Extension Educator Emerita at University of Nevada Cooperative Extension. Reach her at skellyj@unr.edu.