Overseeding lawn

Asked March 20, 2017, 9:24 AM EDT

When can I overseed my lawn?

Polk County Iowa

8 Responses

Mid-August through mid-September is the best time to overseed a lawn in Iowa. Overseeding in spring often results in more weeds than grass.

An article on overseeding can be found at the website below.

We have a LOT of quack grass in our lawn according to a turf expert. She suggested we overseed during the times you mention above, but also said to do it again in the spring to choke out the quack grass. What are your thoughts on this?

Quackgrass is a perennial grass. It is extremely difficult to control.

Overseeding will not choke out quackgrass.

Several repeat application of glyphosate (Roundup), applied over a period of three to four months, will likely be necessary to kill quackgrass. Glyphosate is a non-selective herbicide that kills virtually all plants (both desirable and weedy) to which the material is applied.

Is there an organic option? We're hesitant to use chemicals like Roundup.

Quackgrass spreads via underground stems or rhizomes.

The only non-chemical option is digging. The quackgrass needs to be dug up and all the roots and rhizomes removed from the soil. Digging and the removal of roots/rhizomes would need to be done on a regular basis throughout the growing season.

We're learning a very hard lesson. We had a 100 year old locust tree split on our property and had to be removed. The company that did the stump drilling filled the area with black soil as well as other large divots made by the falling branches. The result appears to be bad soil full of weed seeds. The quack grass pretty much covers our entire front lawn. It took us a year to figure out what was going on. Should we "Roundup" the whole front yard? If so, when is the best time to do that so we can reseed in the fall?

Glyphosate (Roundup) is most effective when applied to plants that are actively growing. Wait until the quackgrass is green and actively growing (late April or early May) and apply Roundup to the quackgrass infested areas. The initial application will kill the above-ground growth and a portion of the plant's root system and rhizomes. Surviving roots and rhizomes will send up new growth within a few weeks. Spray the new growth with Roundup. Continue this process through June, July, and August. By late August, most of the quackgrass will hopefully be destroyed. Overseed in early September.

Thank you, Richard. We'll give it a try.