As we shift full gear into summer, your once lush green lawn can start to look tired and brown thanks to high temperatures and lack of moisture. In our area, most grasses are “cool season” grasses – they thrive primarily in spring and fall when temperatures are between 67o F and 75oF. As temperatures climb to about 85o F, cool weather grasses begin to go dormant. This is because cool season grasses have a type of photosynthesis and transpiration that slows in higher temperatures. Dormancy is a defense mechanism that lets the grass reserve its energy and resources such as nutrients and water.
Heat stress and drought stress often go hand in hand. As temperatures rise, so do soil temperatures. Moisture evaporation causes soil to contract and even form a crust, further drying out the soil and preventing grass from getting sufficient water which can trigger dormancy just as heat stress can.
How To Spot Heat Stress in Your Lawn
How can you spot heat stress in your lawn? Here are some clues:
- Foot prints that remain on your lawn – as grass loses moisture, it loses its resiliency, and doesn’t bounce back after being walked on as it does when it is properly hydrated.
- Rolling or folding of the grass leaf blades is an early indicator of drought stress.
- Brown spots or all over browning – Brown grass isn’t necessarily dead grass – it is often just dormant. You can test this by pulling on brown grass. If the grass is still viable, its root system will still be strong and it will be difficult to pull out. If it slips out easily when pulled, the grass may be dead or being attacked by grubs.
- A purplish cast – The purplish cast is due to a reduction in chlorophyll as photosynthesis slows due to the onset of dormancy.
How To Handle Heat Stress In Your Lawn
In a healthy lawn, dormancy is a state that can be weathered without lasting damage. A good root system is imperative for a healthy lawn, which is why feeding your lawn in the spring and fall, along with proper watering to encourage deep root growth, is essential.
When it comes to watering, deeper and less frequently is the way to go. Well-watered soil will begin to dry from the top, which encourages roots to grow towards the moisture deep in the soil.
Once your lawn begins to go dormant, you should avoid watering unless you plan to water all summer long. If you water just enough to shift the grass out of dormancy, the grass roots – which will have been depleted of food reserves during dormancy – will leave your lawn more susceptible to further heat and drought stress as well as more vulnerable to diseases and insects.
You should avoid having your lawn go dormant if you have a new lawn that you are trying to establish. In this case, the root system of the new lawn will be too immature to sustain a period of dormancy well, and you may lose some or all of your lawn post-dormancy.
Need more tips on keeping your lawn lush and barefoot ready? Call us at Farmside – from helpful advice to installing irrigation systems, we can help you have the lawn of your dreams!