(Radio Iowa) – Some 600-thousand central Iowans are now forbidden from watering their yards in most cases, but an expert at the Iowa State University Extension says it won’t necessarily mean our lush, green grass is doomed. Aaron Steil, a consumer horticulture specialist, says many Iowans’ lawns are comprised of Kentucky bluegrass and fescues which naturally go dormant in the heat of summer.
“The leaves turn brown, but the crowns and the roots remain alive. And if we irrigate, they don’t go dormant. If we’re not allowed to irrigate, they will go dormant, and there’s nothing wrong with that,” Steil says. “It’s actually a natural process that these grasses go through, and it can stay dormant for up to six weeks without any long-term damage.” What happens if we have little rain for the next six weeks and we still can’t water our lawns?
“You may see some dieback,” Steil says. “It usually ends up being kind of patchy dieback, but the silver lining here is that the best time to repair that damage is in September after things start to cool off, the lawn can green up again and you can repair that damage by reseeding at that time.” The Central Iowa Water Works issued an alert this week, banning most outdoor watering, not due to a lack of water, but because of high nitrate levels in the source rivers.
If the ban lasts much longer, Steil says something that will help your lawn is to raise the cutting height of your lawn mower. “Raising the height allows the grass to have more leaf surface area, which promotes a deeper root system, making it more resilient to dry periods or drought periods because the root system is just deeper and more extensive,” Steil says. “The other thing that’s nice is that taller grass will shade the ground, which would reduce evaporation from the soil surface.”
For those Iowans who are still allowed to water their lawns, you don’t need to water all the time. Steil says it’s actually better for the lawn to water infrequently.”If we water a little bit all the time, the roots have no reason to get any deeper, and then these shallow roots are much more prone to damage if conditions get dry,” he says. “You want to make sure that you water very deeply, that you’re wetting the soil down several inches to promote good deep root growth that is then more tolerant of dry periods.”
If your lawn goes dormant, Steil says to hold off until early fall on using any fertilizer, as the nutrients will won’t be taken up. He also notes, while lawn irrigation is restricted, newly planted trees, shrubs and other garden plants can still be watered responsibly.
