Just like I predicted: June was hot and dry.
Fans and window air-conditioning units were turned on before we wanted to. Upstairs bedrooms were too hot to sleep in. The Animas River seemed appetizing but was moving way too fast for us to trust youngsters in. The temperature hit 99 degrees during afternoon baseball games in Farmington, with a wind that felt like it could take every ounce of moisture from your mouth and a sun that could blister your shins in less than 20 minutes.
OK, some of that is a bit of an exaggeration, but it was another brutal June. And know that plants were none too happy about it either. Every year, I seem to get that one plant that is water-stressed from the moment I put it in the ground. Perhaps it didn’t have the strongest root system in the pot; perhaps I didn’t dig the hole wide enough; maybe I left it in the pot on the front porch too long and over-stressed it. Who knows? And every year, parts of the lawn show drought stress much more quickly and end up turning yellow too early.
Without fail, the lawn always looks green and healthy come mid-May. There is ample soil moisture, nutrients are being released into the soil solution (water) and the warm days and cool nights are the favorites of our cold-season grasses. But as homeowners, if we are not careful, June can take that lawn by surprise and our predominant lawn-grass species, Kentucky bluegrass (Poa pratensis), may become stressed and start to yellow.
Now, we all know that Kentucky bluegrass loves water, but really, most turfgrass species love water. (There are some exceptions that are much more drought-resistant, and those will be the topic of next Saturday’s Get Growing column.) But if they don’t receive enough water, especially when daytime temperatures are above 90 degrees, they can go summer dormant. It’s actually a pretty impressive environmental adaptation: when stressed, shut down. In most cases, that is what we see in the summer, especially before our rains start to fall.
Kentucky bluegrass allows its leaves to die but keeps the crown (the origin of new roots and shoots) alive. It can generate new roots and shoots from its rhizomes. When cooler nights and rains return, the grass can recover and put on new, green growth. If you are comfortable with your grass turning yellow and going dormant, great. If those rains don’t come and drought conditions persist, you may see damage to the turf.
To alleviate some of that stress, remember the rule of thumb for watering an established lawn: “Water as deeply and as infrequently as possible.” Deep and infrequent irrigation stimulates root growth, resulting in healthy, drought-tolerant and pest-resistant turf. So plan on applying 1 to 1.5 inches of water per irrigation. Measure this by placing shallow tins around the lawn and allow the irrigation to go for 10 minutes. The average depth of water multiplied by six is the inches of water per hour. Irrigate between the hours of 10 p.m. and 6 a.m., which tend to overlap with the turf’s natural dew period.
And lastly, let the turf tell you when it needs to be watered. Look for signs of wilt, which tend to show up in the same place. The blades of the grass can fold and footprints can remain visible on the turf for over a half an hour. Kentucky bluegrass can be a water hog, but as homeowners, we are frequently guilty of overfeeding it.
Darrin Parmenter is the director and horticulture agent of the La Plata County Extension Office. Reach him at firstname.lastname@example.org or 382-6464.Darrin Parmenter