Too much rain could wash away the fertilizer before it has a chance to soak into the soil, so plan to fertilize several days before a heavy rain arrives or several days later.
Will Rain Wash Away Fertilizer? The problem with fertilizing just before heavy rainfall is that the water won't have time to slowly filter down into the ground and deliver the nutrients where they need to go. Instead, it will simply wash your fertilizer into the nearest storm drain.
Mild rain after you fertilize is nothing to worry about. But a downpour, or several days of consistent rain, can be a problem.
“I don't recommend fertilizing before or after a heavy rain because the fertilizer can be leached out of the soil or washed away before it can be consumed by the root zone,” Clarke says. Instead, the best time to fertilize the lawn is right before a light to moderate rainfall.
Rain After Fertilizer -- Granular Applications
Granular fertilizer and insecticide applications need to be watered in. This activates the product. Slow-release granular fertilizer is not easily washed away and doesn't dissolve quickly in water. So rain after fertilizer is actually a good thing.
You can usually apply most non-liquid granular fertilizers to wet grass, but not saturated ground. If there are ponds or heavy rain, it's best to wait until the ground processes the water before applying any type of fertilizer. If there's light rain, it's okay to spread dry granular fertilizer.
Light rain — when the precipitation rate is < 2.5 mm (0.098 in) per hour. Moderate rain — when the precipitation rate is between 2.5 mm (0.098 in) – 7.6 mm (0.30 in) or 10 mm (0.39 in) per hour. Heavy rain — when the precipitation rate is > 7.6 mm (0.30 in) per hour, or between 10 mm (0.39 in) and 50 mm (2.0 in) per ...
If you would rather not waste your time and the money you've invested, it's best to fertilize when no rainfall is expected for two days, or spread the fertilizer before it rains if you're anticipating only light rainfall. The light rainfall can substitute for watering in the fertilizer after application.
Early morning is the best time of day to fertilize your lawn. Fresh morning dew provides just enough moisture for your grass to absorb the fertilizer.
Don't fertilize when it's winter or early spring
Your lawn needs an extended period to recover from the cold weather. Fertilizing in this season may cause your lawn to become weak and sickly. The ideal temperature to fertilize your lawn is 50-70 degrees Fahrenheit.
Late afternoon or early evening (when there's still light, of course) is the best time of day to apply lawn fertilizer. Applying it in the heat of a scorching afternoon can cause the sun's rays to burn your grass—and when your goal is “lush and green,” burned grass blades simply won't cut it.
Mowing and fertilization are essential aspects of lawn care during your grass's growing season, and the time to do both can sometimes overlap. Although it's tempting to mow and fertilize on the same day to save time, it's far better to mow a few days before fertilizing.
At Master Lawn, we typically say to wait 24 hours before watering your lawn after fertilizing. But it is important to make sure that it does receive a good watering session soon after that 24 hour waiting period. Watering helps the fertilizer to activate and to break down and begin feeding nutrients to the lawn.
It is best to wait a day or so after a rain before applying fertilizer. At this time, any pools of water will be gone, but the ground will still have moisture in it. Do not apply fertilizer on grass blades that are still wet. Check the forecast and make sure some sunshine is in order.
The answer not very cut and dry, but here is the bottom line: The vast majority of the time, rain after a fertilizer application is not a problem at all. In fact, it is usually a good thing.
Can I fertilize my lawn every 2 weeks? To avoid over-fertilizing, applying a fertilizer every two weeks is not recommended. Fertilizing as often as every two weeks will likely lead to problems such as lawn burn, excessive grass growth, as well as polluted water that can lead to toxic algae growth.
'As long as your blades are sharpened, and the grass isn't not soaking wet, mowing in the early morning dew is totally fine,' says Douglas Dedrick.
We recommend waiting 24 hours after fertilizing to water your lawn, which will give the fertilizer time to settle. After the 24 hours are up, it's important to give it a good soak—not just a quick spritz with your hose—to activate the fertilizer and help the critical nutrients absorb into the soil.
Tips for applying granulated fertilizer
Always wash fertilizer granules off of foliage. Activate the granulated fertilizer by watering it in right after applying.
It only takes between two to four weeks for quick-release lawn fertilizer to be absorbed completely. What is this? Slow-release fertilizers take much longer to break down, so it takes more time for all the nutrients to be absorbed by the soil and grass plants.
Lawn Problems Caused by Excessive Rain and Over Watering
Disease caused by fungus – Too much water can cause grass roots to rot and can lead to disease which starts off as yellow patches in your yard; once fungus sets in, little can be done except reseeding the dead patches in the fall.
If there is no rain in the forecast, by all means, water it in yourself. Otherwise, you're just throwing away good materials. If you're working with a pelletized fertilizer, the pellets will dissolve like sugar cubes and spread out, covering virtually all of the soil.
One (1.00) inch of rain – A light moderate rain never reaches this amount, heavy rain for several hours (2-5 hours). There would be deep standing water for long periods of time.
Rainfall rate is generally described as light, moderate or heavy. Light rainfall is considered less than 0.10 inches of rain per hour. Moderate rainfall measures 0.10 to 0.30 inches of rain per hour. Heavy rainfall is more than 0.30 inches of rain per hour.
An inch of rain is exactly that, water that is one inch deep. Per the USGS Rainfall Calculator, one inch of rainfall equals 6 gallons of water per square yard or 27,154 gallons of water per acre!