Watering Grass At Night Myth [Debunked]

There are many myths around lawn care, what to do, or what not to do and in this article, I will take a dive into and look at the watering grass at night myth.
Depending on the advice you read the myth suggests that watering your grass at night is the best time to water your lawn whereas if you read other advice it will suggest that watering your grass at night is the absolute worst time, so what is the truth?
There are so many myths around gardening and lawn care that it can be confusing when you are deciding what advice you should actually follow and what advice you should ignore.
The truth about all the confusing and contradicting advice you may find on the internet is that there is only one way to really figure out what is correct and that is to take action and learn from experience.
I have loads of experience and have made many mistakes along the way.
I hope you enjoy reading my blog as the whole idea is that you can learn from my experience and mistakes I have made so you don’t have to make the same mistakes.
You can learn a lot from making mistakes but you can also learn a lot from the mistakes someone else makes, lets now take a look at this myth…
Watering your grass at night is not a good idea as it will promote the growth of fungus, mold, and mildew. The myth started because more water will be absorbed before it can evaporate at night. Avoid watering during the hottest times of day but watering grass at night should remain a myth and not a plan of action.
Check out my article on some of the best sprinkler systems.
Why do people say you should water your lawn at night?
It is cool at night and that is one of the main reasons people say that is when you should water your grass. If you water your grass at night when it is cool you would think it would be more efficient than watering during the day when more of the water will evaporate because of the daytime heat.
Watering your grass in the cool of night will enable more of the water to be absorbed down to the deep root area of your lawn and that after all is the area you want the water to get to.
You might not know it but grass really doesn’t like to be in cold and damp conditions and that is why I would always avoid watering my grass during the night when the water will sit on the grass as it won’t be hot enough to evaporate.
Watering your grass at night will achieve the water getting down to the deep root area but the fact any water that sits on the grass leaves and doesn’t get to the soil will potentially cause fungus, mold and all sorts of problems to start on your grass I would say that if possible you should avoid watering your lawn during the night.
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Is it better to water grass in AM or PM?
If your grass is dying because of drought and it needs water it doesn’t really matter that much what time of day you apply the water, the most important thing in this situation is to get your grass a feed of water.
However, if your grass isn’t in dire straits and dying because of lack of water it is best to water your lawn at the optimal time that will result in the maximum amount of benefit for your grass.
It is definitely better to water your grass during the AM hours.
The advantage of watering your grass in the AM hours is that it should still be damp during the hottest period of the day which should protect it from suffering from drought or heat stress.
You should water your lawn as early as possible and before the midday heat arrives because depending on where you live most of the water could evaporate before it gets absorbed down to the deep root area where your grass needs it most.
If you have a sprinkler system you may want to set it to turn on before sunrise at say 5- 6 am in the morning, that’s the earliest I would water my grass.
If you decide you want to water your lawn during the PM hours I would do it during the evening but you definitely want to water it early enough so that the water has time to evaporate from the surface before the cool of night because any standing water during the night will encourage mold and fungus to start growing.
Check out my article on lawn care tips for dummies.
Why is watering the lawn at night a bad idea?
You should definitely avoid watering your lawn at night and keep it as a myth if you want your grass to grow healthy and disease-free. If the early evening is the only time you can possibly water your lawn then that will need to do but watering any later than that should be avoided.
Watering your grass at night may seem like a good idea because the cooler temperatures will allow more of the water to be absorbed before it can evaporate.
Some of the problems that can arise from watering your grass at night are:
Fungus – when you water your grass at night the soil will stay damp for far too long to be beneficial to grass growth. The damp conditions that arise from this are ideal for fungus so if you notice any mushrooms starting to grow on your lawn this is a good sign you need to change your watering routine.
Weeds – If you water your grass at night this will make the soil conditions not ideal for your grass to thrive and grow healthy. When your soil is not in ideal condition for grass that is when weeds can start to invade and take over your lawn. If weeds such as crabgrass, nutsedge, or dandelions start to appear on your lawn you need to stop watering your grass at night.
Patches – if you start to notice patches appearing on your lawn it is a sign you are doing something pretty major wrong, like overwatering which can be caused by watering at night. If you notice any yellow patches, rust-colored patches, or even bare patches appearing this is a good sign you need to change your watering routine.
Is it bad to water grass on a hot day?
If you can avoid it I wouldn’t recommend that you water your lawn during the middle and hottest part of the day because most of the water could evaporate before it gets down to the deep root area of your lawn and that’s where it’s needed most.
When most of the water is evaporating before it gets down to the deep root area this will encourage the roots to become shallow as they will be no use growing deep when the water they need is all near the surface.
A shallow root system is bad news for your lawn and could possibly lead to a number of problems later on.
If you are expecting hot weather it is best to prepare your grass by watering it early in the morning.
When you water your lawn early in the morning this is probably the best way to protect your grass from the stress it will suffer from the summer heat and drought. When you water your grass during the early morning this will allow the water to get to the deep roots and should help keep the soil cooler during the midday heat.
Watering your grass during a hot day will not cause it to burn, that is just a myth, but to get the maximum benefit you should avoid watering during the hottest time of day.
Check out my article on the sun causing your grass to burn if you water it during the day myth.
Is it OK to water grass when it’s cold?
Yes, it is ok to water your grass when it is cold and I would encourage it as grass needs water no matter what the temperature is.
If you know that there is especially cold weather on the way you should make sure your grass is watered as this will actually help protect your grass from potential damage the cold weather can cause.
It’s best to water your grass a day or two before the cold weather arrives as this will give your lawn enough time to fully absorb the water.
Watering your grass will actually make it stronger and more able to deal with the cold weather, this is because water will hold its heat longer than plant tissue will so that means you want your grass to be fully hydrated when cold weather hits it.
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How often should you water your grass?
When it comes to how often you should water your grass a lot of it will depend on your local climate.
It is best to water your grass when it needs it and not just blindly follow a routine at set times.
How do you tell when your grass actually needs to be watered?
The easiest way to tell when your grass needs watered without using any sort of tools is to simply walk across your grass. If the grass bounces back up after you have walked across it, that means it is in fine health and doesn’t need to be watered.
If when you walk across your grass it does not bounce back and it actually leaves footprints, that is a sign you need to water your grass.
It is important that you do actually water your grass only when it needs it as this will promote healthy deep root growth as the grass will have to search for moisture.
You should check when your grass needs watered obviously during the summer but also during the winter months as sometimes during winter there might be rain but not as much as your grass would like.
Check out my full article on watering your lawn with a sprinkler system.
Can you over water grass?
Yes of course you can overwater your grass and it is a really terrible idea.
If you actually water your grass at night like the myth you will end up overwatering and that is why it is a bad idea.
It is best to water your lawn deeply but less often. If you water your lawn every day you will encourage it to grow shallow roots because there will always be water near the surface.
Whereas if you give your lawn a deep water only 2 or 3 times per week you will encourage your grass to grow a deep root system and this will lead to healthy grass growing in the long term.
When your lawn has grass with a thriving deep root system it will be more capable of surviving any drought periods as you have already trained it to grow deep down to look for water.
If you overwater your grass it will have a shallow root system and it will survive from water near the surface, so during drought, your grass will struggle to find water like its used to near the surface because the water near the surface evaporates quickest and therefore your grass will struggle to survive any droughts.