Does Watering Grass in the Sun Burn it? What to Know

Watered your lawn in the sun and later realized that grass is drying in patches? We all know that proper watering helps the grass to overcome drought conditions. If the opposite happens then you have a reason to worry. So, does watering grass in the sun burn it?

Watering your lawn in the sun doesn’t burn it. The real cause of this problem is drought, excess salts in the water or too much fertilizer in the soil.

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. This is purely false, and many scholars have come up with the right explanation for this kind of problem.

Does Watering Grass in the Sun Burn It?

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

The heat from the sun will cause your grass to wilt or turn yellow, this means that water is a remedy. Waiting until sunset before watering your lawn means you are prolonging the suffering of grass in the heat.

No matter time of the day or the intensity of the sun, if your lawn exhibits signs of water 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 will also encourage the growth and spread of fungal infections. This is one of the reasons why the grass turns brown despite watering.

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 solar 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 focusing 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.

Why Grass may appear Burnt after 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:

1. Salt Build-Up

Underwatering your lawn in hot summer temperatures can promote salt build-up due to the high rate of evaporation. Water evaporate 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.

2. 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 grass to change its color to brown.  

3. Over-fertilizing

Mixing irrigation water with excess fertilizers can also lead to lawn fertilizer burn. Nitrogen fertilizers contain salts that have a scorching effect when applied in excess. 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?

Summer is characterized by high temperatures during that day, a condition that may cause grasses to wilt and die. It is important to water your grass adequately during a hot summer. How often to water a lawn in summer may depend on the temperature of the day.

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.

The best time to water your lawn in hot weather include:

Early in the Morning

Water your lawn 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.

Watering early in the morning before the sun out also helps to reduce the rate of evaporation. Water will have ample time to penetrate the soil and reach the roots of your grass.

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’s 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 the growth and spread of fungal infections.


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

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

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). It is simply too hot to water your lawn. During hot summer temperatures, 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.

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.

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