Many property owners ask if watering their lawns in the sun will burn their grass. The answer is that water will not cause leaf scorch, don’t worry about the magnifying glass theory.
Heat can cause your lawn to yellow, water will fix that, waiting until night time can only make it worse and may even cause fungal growth. You may also see yellow patches due to salt buildup along with too dry of conditions. Adding fertilizer is great, but if you don’t regularly water the grass you can get salt buildup in the soil from the fertilizers and cause root burn. The real reason why you don’t want to water your grass in the sun is if you do it around noontime, the water will evaporate and will never reach the roots, that is why it is recommended to water in the morning. But, remember, if your grass is looking stressed and in need of water, don’t wait. Give it a drink.