Thiis has been a very dry year in parts of Iowa and lawns have been suffering. Today is the 15th of August, and I have mown my own lawn once in the last 12 weeks and that was to kill the ragweed and trees that were growing in it. I am now getting several calls from people with dry lawns, they mostly center around the following questions?
WILL MY LAWN COME BACK?
The answer is yes if you had Kentucky bluegrass. Kentucky bluegrass has an underground rhizome system that allows it to come back from extended drought periods. The worst drought that we have had in the last 40 years was 1988. Kentucky bluegrass came back fine in the fall after a drought that lasted from early May to mid-September. If you have dead spots, reseed them with a good Kentucky bluegrass blend.
SHOULD I FERTILIZE IN AUGUST OR WAIT UNTIL LATER?
I recommend that you fertilize in August. I plan to fertilize in the next week. When the lawns do come back, the fertilizer will help with recovery. One pound of nitrogen per 1000 sq ft in mid-August would be money well spent. If the rains come and we get some recovery in the next few weeks, follow that up in about a month with another 1 lb of N/1000. If the fall is dry, do not put on the additional application. Wait until spring and apply some fertilizer with your preemergence herbicide at that time. A preemergence herbicide will be very important next spring because the thinner lawns will likely be more prone to crabgrass next year.
HOW ABOUT APPLYING A BROADLEAF HERBICIDE NOW IN AUGUST?
I would wait on the postemergence broadleaf control application until October. You can even do it in November. There will be weeds like dandelion germinating during the recovery period of the lawns and it is best to wait and hit them late in the season.
HOW ABOUT AERATION?
If you have received some rain and the lawn is recovering, core aeration would be a good idea. I would schedule that for a couple of weeks after the fertilizer application.
I predict that we will get rain again and that most lawns in Iowa will recover fine. If you do need to do some seeding of dead areas, the best time is between August 15 and the end of September. For more information on all subjects concerning lawn care, see the Iowa State University extension page at https://www.extension.iastate.edu/turfgrass/search/content?f%5B0%5D=im_field_category%3A3&retain-filters=1 and go to the “publications” section.
The two lawns below are typical of the type of drought damage that has taken place in Iowa this summer.
This is what the rhizomes of Kentucky bluegrass look like. The can survive extensive droughts.