It’s like clockwork, the weather shifts from a cool wet spring to hot summer days! So the number one question we hear in the lawn business is “Why is my lawn turning brown”? Haven’t we received enough rain, that my lawn shouldn’t have brown spots? Let’s take a look at a few reasons why you may be noticing brown spots in your lawn.
What is the difference between Drought Stress vs Heat Stress?
Heat stress is brought on by the sudden change from cool nights to high temperatures during the day. This year we certainly had a wetter than average spring. However, grasses that normally do well in spring and fall can quickly brown out. We see heat stress on grasses that are normally designed for shade, like Fine Fescue. This grass will probably survive in a shaded area, but when the lawn is in the direct sun, this type of grass can quickly go into stress. Cool-season grasses, in general, thrive in temperatures 65 degrees to 75 degrees. As temperatures rise, so does the increase in stress to the grass – after all, it is a living organism.
Here are some easy ways to detect heat stress in the lawn:
- Footprints that remain in the lawn. As turfgrass loses moisture so does its ability to bounce back.
- Brown spots where the grasses look different. Sometimes there can be other factors such as disease activity or insect activity.
- The sudden change from green to brown.
How can you tell if your lawn is going into drought stress?
Drought stress is a response the turfgrass plants have due to lack of available water in the soil. When we have windy conditions and low humidity, it doesn’t take any time at all to dry out the top few inches of soil.
The first signs are a purplish tint to the otherwise green color to the lawn, usually in an area that is exposed to full sun. If you walk across these areas, you will also notice that the grass that you stepped on will not readily return to its upright stance. This is known as lack of turgidity – the plant is not completely full of water.
Upon noticing areas with these signs, you can take a penknife and cut into the soil. If the soil is light in color and does not bind together then it is apparent that the soil has dried out. You can take another sample in an area that is still green and/or in the shade and compare the two samples.
Photo courtesy of our friends at NALP.
What can you do?
First, if you have an automatic irrigation system, run the system through manually and observe that each one of the heads is intact and rotating properly. Both lawn care and irrigation companies are besieged by phone calls in the late spring when temperatures go up and rainfall goes reduces, prompted by defective sprinkler heads or systems that are simply turned off.
Second, if the system is operating properly, you may wish to give the areas that are going into stress more time on your irrigation controller. For example, if it is currently getting 20 minutes of water, try going to 30 minutes, give it a few days and observe the results.
And remember the rule of thumb – it is better to water less frequently and more deeply than it is to water more frequently. Turfgrass plants react to how much water they receive as well as when and how often it is applied. And it really is a rule of thumb. Each and every lawn is unique, indeed there are often many lawns within a single lawn. Some areas use more water than others. You really need to identify these areas and customize your approach.
If at any point in time you have questions about the brown spots in your lawn, please reach out to us immediately so we can help identify whether the damage is heat or drought stress, insect or disease activity.
