Watering your lawn at night isn’t always a bad idea- but it’s not always a good idea, either. Some people advocate watering your lawn at night, especially in dry regions. Others will tell you that watering at night is a surefire way to attract mold or disease. The truth is somewhere in between, but it does lean more toward that second opinion.
Why Some People Believe That Watering Grass at Night Is a Good Idea
Most people that tell you to water your grass at night do so for two reasons. First, they say that watering your lawn at night leads to less evaporation and water loss so you get more for your money and do less harm to the environment.
The second reason people suggest that you should water grass at night is for better absorption. They believe that a lack of sunlight will allow the grass to “focus” on absorbing the water and, as the water isn’t actively being evaporated by the sun, that water has a better chance of being absorbed by the grass.
Here’s the Truth About the Watering Grass At Night Myth
Is it bad to water grass at night? It’s only bad to water your grass at night if you live in a region that’s humid or that has temperatures at night in the 50 F to 80 F range. In a dry region (relative humidity below 20%) with very hot temperatures, watering your lawn any time after the sun has gone down would be fine. In a region that’s humid, however, or with decent humidity and a low to average temperature range at night, you may be setting your lawn up for future issues.
High moisture or temperatures below 80F can create a good environment for disease, mold, or bacteria to spread and thrive when you add even more moisture at night. This is why watering your lawn just after sunset, instead of just before sunrise, can be one of the worst things you can do to your lawn.
What’s more, there aren’t even any advantages to watering your lawn at night. Water doesn’t absorb better when it’s dark and the grass may even absorb less as it is only able to store so much and that water won’t be able to be used until it’s bright and warm again.
The Problems Watering Your Lawn At Night Can Cause
When we’re talking about watering at night, we mean anytime during and after sunset until about an hour before sunrise. If you choose to water your lawn at night, be prepared to deal with the following issues.
Mold and Fungus
Why is watering grass at night bad? Watering your lawn at night is primarily bad as there is little mold loves more than abundant water, cool temperatures, and a dark space. At night, if you water your lawn after the sun has gone down, this describes your lawn. Once your lawn has a fungal infection or once it has begun to sprout mushrooms, it will be very difficult to break the cycle without harming your lawn in the process.
Bacterial Infections (Leaf Spot, etc.)
Just like with mold and fungus, bacteria thrive in cool, damp, and dark conditions. If you water your lawn at night, the water will have a chance to sit on your lawn and will not evaporate for many hours. This gives any bacteria present enough time to either take hold of your lawn or spread faster than it would otherwise.
Root Rot
While watering your grass at night won’t be harmful if done once or twice, doing this on a regular basis, especially if your lawn doesn’t completely dry most days of the week, can lead to root rot over time. To avoid root rot you will need to allow your lawn to drain properly at least 5 nights a week. If your lawn often seems soggy, it is at a greater risk for the problems caused by watering your grass at night.
Slug Infestation
Beyond spores, bacteria, and increased rot, listening to the watering grass at night myth can cause slug infestations in your lawn and any surrounding plantings. Slugs are a common lawn pest and, like mold, can be hard to get rid of once they set in without harming your lawn in the process.
Slugs are both unsightly and can cause physical harm to your lawn by chewing on the blades of grass. This will not only lead to a “gnawed” appearance but can cause brown spots and a higher risk of bacterial or fungal infection over time as the lawn becomes more and more stressed.
Frogs and Toads
While this might be a more niche problem that can come about when you regularly water your lawn at night, it is worth mentioning. No matter where you live, if you are the only household in your neighborhood that waters their lawn at night, every night, and there is wildlife nearby- the frogs may find you. They will find anywhere that collects water, especially in the spring, and they will sit there. Your lawn could be covered in frogs every single night.
These frogs or toads could even bury themselves into your lawn, leaving holes. This is very common in places like Missouri or other regions of the Midwest with rivers or swamps nearby. The frogs can infest rain barrels and gutter spouts or drains as well and lead to blockages. Watering your lawn at night is an open invitation for frogs and toads.
When Should You Water Your Lawn Instead?
The best time to water your lawn is half an hour before sunrise or, if you forget or your sprinklers failed to go off, any time before the dew has dried on your lawn. Watering your grass while it is still somewhat dark, before things warm up, allows the water to soak in as much as it can over a few hours. The excess, if there is any, will then dry up quickly before it has a chance to cause any disease.
Further, watering your lawn early in the morning, as opposed to watering your lawn during the middle of the day, will reduce waste due to evaporation. Setting a timer on your sprinkler system for an hour before sunrise, typically around 5 am, can help improve distribution by providing better water pressure as very few other systems will be drawing water at the same time.
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