How can lawn treatments help keep grass healthy during hot weather?

Fighting lawn care in the heat of summer is a constant struggle to overcome the physical properties of water and the soil. Evaporation outpaces irrigation, the soil can become hydrophobic, and grass roots unable to penetrate to pull the moisture through for the plant. Yes, this means that simply watering more is not enough. Learning how to modify the soil to enable water to penetrate is key to a healthy lawn in hot weather. But learning how to modify the soil in hot weather is not easy. The changed characteristics of the soil through the heat of summer can vary from week to week. The only way to be sure that your modifications are effective is to test and reapply as necessary.

Understanding soil hydrophobia and water penetration

Most lawns deal with a few weeks of warm to hot weather in the summer and fall. The battle to water a lawn in hot weather is a battle to the laws of physics. Water will evaporate faster than you can apply it, the soil will become hydrophobic, and the grass roots will not be able to absorb the water that does penetrate the surface of the soil to keep it a healthy green color.

The condition of hydrophobic soil is generally caused by extreme weather events. In general the most dramatic change in soil’s condition to become hydrophobic occurs with the extreme heat and dry weather that allows the organic matter in the soil to decompose rapidly. In this decomposition process water-repelling compounds are released that form a waxy coating on the soil particles. This coating has an effect of repelling water and can be especially evident in sandy soils. As sandy soils already have large interstitial spaces between the individual soil particles, these water-repelling compounds can penetrate into the soil very quickly, coating the entire soil mass. The water then has difficulty penetrating the soil surface, running off of the lawn in small streams, collecting in low lying areas of the lawn, and not becoming available to plants for long periods of time.

On the market, you can find a range of Wetting Agents. These treatments dissolve the water-repelling coating found on the surface of the soil particles. As a result, water can penetrate the soil as normal to aid growth.

Immediate relief is available for lawns that are suffering from water stress. For example some wetting agents are more useful than others for use on stressed lawns. Other wetting agents are best to apply prior to soil becoming severely hydrophobic and early summer is the ideal time to apply a soil conditioner / wetting agent to your lawn to help it withstand the higher temperatures and dry spells of the summer months.

Moisture retention strategies

The moisture that is introduced into the root zone of the lawn needs to be retained for adequate periods of time in order to satisfy the moisture requirements of the grass in the lawn. If water can be introduced into the root zone of lawns then it is relatively easy to ensure that moisture is retained for the required time in lawns in order to provide the lawn with an adequate supply of water to satisfy the moisture requirements of grass in lawns during periods when moisture in the air is low.

For lawn care, during hot weather water turns into enemy number one for lawn grass, and in order to fight this battle it is necessary to prolong the time that water is available to grass roots. While for normal growing grass of all types deep but less frequent watering is preferred, in order to supply grass roots with moisture during periods of hot weather it is beneficial to extend the time that water is available to them. Aqua Force wetting agent helps extend the time that water is available to grass roots by improving soil structure to penetrate more easily into the soil and by reducing the rate of drainage from the root zone of grass. As a result, moisture from applied water is available to grass roots for a longer period of time.

Controlling the temperature of the soil is another way to help enhance the moisture retention. The thatch on your lawn for instance will provide the necessary insulation to keep the soil beneath it cool. This in turn will prevent fast evaporation of moisture from the soil below. A number of lawns have excessive thatch which can be bad for moisture to enter the soil. And then there are lawns that don’t have enough thatch to keep the soil cool, which again causes fast evaporation of moisture from the soil. Both of these scenarios are not ideal.

Using Organic Matter: Organic matter will improve the ability of your lawn to hold water in the soil for the grass roots to use. As the organic matter breaks down it will work its way into the soil structure to improve the lawns ability to hold water. Spring applications of compost as a top dressing are recommended to have better moisture retention by summer. However, it will not cure any existing heat stress problems.

Fertilization timing and heat stress

Don’t Over Fertilize Your Lawn In Hot Weather. It’s well known that cool-season grasses require more nitrogen than warm-season grasses in order to thrive. However, during the summer months most cool-season grasses are dormant and don’t require any additional nitrogen to grow. However, the excessive amount of nitrogen that most lawn fertilizers contain can promote excessive new growth. This newly grown grass will quickly become stressed, turn yellow and can die within a short period of time when there is little to no water available to it. A better lawn fertilizer for summer months would be a well balanced fertilizer that contains a higher concentration of potassium. It will help your grass to get through the toughest of times.

On the other hand, Potassium is one of the compounds that help strengthen the grass plant to survive heat stress. In addition, it helps to enable the grass plant to take up water when needed. So, for the months before hot weather a balanced lawn fertilizer that has a reasonable amount of Potassium will be the best lawn fertilizer for your yard.

One common error in lawn care for lawns suffering heat stress is applying high nitrogen grass fertilizers in an attempt to make the lawn “recover quickly” from any damage already done. This can even place additional stress on a lawn suffering from heat stress.

Preventive treatments vs. reactive solutions

Preventative or reactive lawn care for warm weather? Either way the best approach is to start to apply products and other lawn care methods before weeds, drought stress and lawn pests cause problems on your lawn. See the above section on how to apply a pre-emergent herbicide for example.

Pre-emergent herbicides, applied prior to weeds emerging from the soil and competing with your lawn for water during a drought, and soil conditioners, applied prior to your soil becoming severely hydrophobic, are just two examples of preventative lawn treatments. Anti-desiccant sprays are also available, which are sprayed on the blades of grass to form a protective film on the grass. This film stops water from being lost through the process of transpiration.

Once your lawn has been stressed to the point of turning brown and becoming crispy, it can be repaired but the best that can be hoped for is a return to previous health. This is known as reactive treatment and is the complete opposite to how lawns should be treated for hot weather. In essence, it is like closing the barn door after the horse has bolted.

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Long-term soil health improvements

Make you lawn more healthy by increasing the amount of organic matter in your lawn and improve the structure of your lawn to allow deep root growth. This type of lawn will allow your lawn to survive through hot dry weather. It may take several years to develop a lawn of this type but it will be able to deal with heat stress year after year.

Fix any problems your lawn’s soil may have, for example the pH could be wrong or it could be lacking in nutrients for grass. These problems are best addressed during the cooler part of the year and will take a few months to start to have an effect. Applying soil amendments in the spring will have the optimal affect the following summer.

All lawns experience stress during the hot summer weather. However, lawns that have been serviced by a lawn care company that focuses on improving the lawn’s health over the long growing season will experience less decline than lawns that do not have deep root systems. A lawn that has been serviced in this manner will be able to go for longer periods of time without watering and will decline less rapidly when it is watered than lawns that have not had long term health care. A well cared for lawn such as this requires less maintenance during the hottest time of the year.