You should fertilize your lawn a day or so after a light rain or using a sprinkler. This prevents the application from being washed away.
“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.
Timing: Apply fall lawn fertilizer once between August and November, right before winter hits, 6 to 8 weeks after the summer feeding.
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.
Rain After Fertilizer -- Liquid Applications
While liquid fertilizers are water soluble and have slow-release properties similar to granular products, they hold onto the plant material and organic matter when sprayed and the plant quickly absorbs them. But they need 30 minutes of drying time before becoming rainfast.
You should fertilize your lawn a day or so after a light rain or using a sprinkler. This prevents the application from being washed away. The moisture gets your soil damp and ready to receive nutrients. Do not apply fertilizer before or after heavy rains.
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.
Ideally, you'll want to mow and rake before fertilizing, so that excess lawn waste is removed and the fertilizer will have an easier time reaching the soil.
Watering after fertilizing washes the fertilizer off of the grass blades and into the soil, where it can get to work nourishing your lawn. It's also important because if fertilizer sits too long without being watered in, it can burn the grass.
If fast results are desired, lightly water the product in after application; however, watering-in is not required.
If done too early you could be inviting damage from the winter weather, such as snow mold. The best time to fertilize can depend on the climate, but typically September and October are usually the best months to apply fall fertilizer.
When To Fertilizer Your Lawn in the Fall. The best time to apply your last fertilizer application is between August 15 and October 1. Ideally, your last lawn feeding should take place six to eight weeks before the average first frost in your area.
Fast-release synthetic lawn fertilizers work within 24 to 48 hours after application. Slow-release fertilizers work more slowly, but they are less risky to use. Synthetic slow-release products work in 2 to 5 days, while organic slow-release versions work in 2 to 6 weeks.
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.
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.
Fertilizer and Water
A day or two before applying fertilizer, water your lawn thoroughly. After grass dries, apply fertilizer. Then lightly water again. This second watering is vitally important, because it washes fertilizer off grass blades and into soil.
Doing anything too drastic on your lawn, such as cutting your grass, will disrupt this process. We always suggest to our clients that they wait 24 to 48 hours before mowing their lawn after fertilization. Ideally, our customers have mowed right before we fertilized their lawn, so this waiting period won't be an issue.
While the best method for determining exactly how much fertilizer is needed is a soil analysis conducted by a laboratory, most cool-season grasses require 2 to 4 pounds of nitrogen per 1,000 square feet each year, and a majority of this nitrogen should be applied in two fall applications; one in September and the other ...
Best Fall Lawn Fertilizer
While this fall lawn fertilizer dose is important, an application at the end of October or early November is essential. At that time, apply a fertilizer with a formula of 13-25-12. The push of phosphorus will stimulate root growth through November and even into early December.
You just have to be careful about the order: always mow before fertilizing if you want to do both on the same day. Mowing the lawn before fertilization on the same day helps the fertilizer spread more evenly.
Allow 24-48 hours, depending on the label, after applying most synthetic fertilizers before any pets, kids or pregnant women walk on the lawn. Water the lawn and allow to completely dry before using the lawn after fertilizing.
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.
However, you should plan to water-in with rain only when the rainfall is expected to be steady and not heavy or intense. Heavy or hard rain can easily flood the grass and wash the fertilizer off of the lawn and into the storm sewer system.
Always follow the manufacturers recommended rates and application methods. Fertilize outdoor plants in the coolest part of the day, such as early morning or late evening, especially in hot summer weather. Always water in fertilizers well to distribute nutrients throughout the soil profile and to prevent burning.