Find Out: Does Watering Grass in the Sun Burn It?

Watering your lawn in the sun doesn’t burn it. Many gardeners believe in a myth that water droplets act as a magnifying lens that focuses the sun’s energy on grass blades to cause scorch. However, the real cause of this problem is drought or excess salts in the soil. Therefore, it’s high time to put this myth to bed.

According to an article on Washington State University’s website written by PhD horticulturist Linda Chalker-Scott, brown or dead spots of grass in your lawn are not caused by water droplets baking in the sun. Instead, the burns are caused by salt accumulations and other water pollutants. 

No matter the time of day or intensity of the sun, if your lawn exhibits signs of heat stress, you should go ahead and water it. Postponing until the sun has gone down will continue to hurt the grass. Watering close to nightfall, on the other hand, will also encourage growth and spread of fungal infections.

According to a team of researchers from Eotvos University in Budapest, Hungary, there is no evidence that watering your lawn on a hot day could burn it. Water droplets that accumulate on grass blades are unable to focus sufficient sunlight’s energy to cause damage.

Water droplets need to be at a certain distance from the grass blade’s surface to burn it. Therefore, it cannot scorch the grass unless it is suspended in the air for a certain period of time to focus the sun’s energy on the grass. 

The researchers also found that water droplets evaporate much faster than they could cause damage to the grass on a sunny day.

Grass Dying Despite Watering

If your lawn is appearing burnt after watering on a sunny day, it can be due to agents in water like chlorine, salts, and high fertilizer content. Let’s have a look at each of them:

Salt Build-Up

Under-watering your lawn in hot summer temperatures can promote salt build-up due to the high rate of evaporation. Water evaporates quickly, leaving behind high concentrations of salts in the soil, which can burn your lawn grass. Using salt water to irrigate your grass also increases the chances of salt buildup.

Water Pollutants

Excess chlorine, acid rain, and other water pollutants can drastically lower soil quality, which contributes to the poor health of your grass. Water pollutants can also change the soil pH. Excess soil acidity will cause your lawn to exhibit different symptoms, including change of color to brown.  

Over-fertilizing

Mixing irrigation water with excess fertilizers can also burn your lawn. Nitrogen fertilizers contain salts that have a scorching effect when applied excessively. It can also combine with other elements in the soil to create unfavorable conditions for grass to thrive.

What is the Best Time to Water Grass in Hot Weather?

Hot weather signifies the start of high summer temperatures during the day. High temperatures can cause your grass to wilt and die when not watered adequately. So, what is the best time to water your lawn in hot weather?

Early in the Morning

The best time to water your lawn in hot weather is early in the morning, before 10 am. During this period, the grass will be able to absorb enough water to sustain itself throughout the day before it gets too hot. Cool mornings help to reduce the rate of evaporation, giving water ample time to reach the grass roots.

Midday

Midday is not particularly the best time to water your grass. Perhaps if you forgot to water your lawn in the morning and realize the grass is showing signs of water stress, it’s not a bad idea to water it in the heat of midday sun. 

Watering your grass when the sun is shining will reduce heat stress and cool the plants. However, plenty of the water will be lost through evaporation. Watering your lawn in the sun will not burn your grass, as it’s believed by many gardeners. 

Late Afternoon

Late afternoon, between 3 p.m. and 4 p.m, is the second-best time to water your grass. If you had a tight schedule in the morning and forgot to water your grass, this is the best time to do so. The grass leaves will have enough time to dry before the night falls in. Watering past this time is highly discouraged as it promotes growth and spread of fungal infections. 

Note: Late at night is the worst time to water your grass. It increases the risk of fungal diseases.

What Temperature is too Hot to Water Grass

It’s not ideal to water your grass when the temperature is above 95 degrees Fahrenheit (35 degrees Celsius). Water will evaporate fast before it reaches the roots of your grass.

The ideal temperature range to water your lawn is between 60 and 70 degrees Fahrenheit (16 and 21 degrees Celsius). At this temperature range, the grass is able to absorb enough water to sustain itself for several hours or days, depending on the weather conditions.

If you live in areas that experience high heat and humidity during the day, the best time to water your grass is early in the morning. The water will have a chance to soak into the soil to reach the roots of your grass before it evaporates.

Not watering long enough in hot summer weather conditions can be detrimental to your grass. It’s ideal to water your lawn deeply and less frequently than light and more frequently. 

If the temperature range is between 70 and 80 degrees Fahrenheit, water your lawn with half an inch of water. However, if the temperature is above 90 degrees Fahrenheit, it’s best to increase the ratio to 1 inch of water per session.

Final Thoughts

Watering your lawn when the sun is shining doesn’t burn the grass. In fact, it helps to hydrate and lower the temperature of the plants. However, you should not water your lawn when the temperature is above 95 degrees Fahrenheit. The water will evaporate before it reaches the roots of your grass.