Does Watering Grass in the Sun Burn it? Solved

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. 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, excess salts in the water or as a result of too much fertilizer in the soil.

Does Watering Grass in the Sun Burn It?

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

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

No matter time of the day or 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 a nightfall 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 sun’s energy to cause damage.

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

The researchers also found that water droplets evaporates 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

Under-watering your lawn in hot summer temperatures can promote salt build-up due to 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-build up.

2. Water Pollutants

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

3. Over-fertilizing

Mixing irrigation water with excess fertilizers can also lead to lawn fertilizer burn. Nitrogen fertilizers contain salts which 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. An increase in temperature during the day plays a huge role in determining the best time to water your lawn.

So, what is the best time to water your lawn in a 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 themselves throughout the day before it get too hot.

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


Mid-day 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 exhibiting signs of water stress, it’s not a bad idea to water them in the heat of midday sun.

Watering your grass when 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’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 growth and spread of fungal infections.


Late at night is the worst time to water your grass. It increases the risk of diseases. Fungus are usually present in soil, they munch on decomposing leaves and other organic matters. However, they may rise up to the grass when the conditions are warm and moist.

What Temperature is too hot to Water Grass

It’s not ideal to water your grass when temperature is above 95 degree Fahrenheit (35 degree Celsius). It is simply too hot to water your lawn. During hot summer temperature, water will evaporate fast before it reach the roots of your grass.

The ideal temperature range to water your lawn is between 60 and 70 degree Fahrenheit (16 and 21 degree 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.

The chances of lawn diseases are reduced when watering in the morning. The grass blades will have enough time to dry off and hence preventing fungal infections that are common during hot summer days.

Watering your lawn early in the morning can also prevent the likelihood of grass becoming dormant during high summer temperature month.

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 frequent than light and more frequent.

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

Final Thoughts

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

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