Timing: Apply fall lawn fertilizer once between August and November, right before winter hits, 6 to 8 weeks after the summer feeding.
The first thing to know about fertilizer is the formula. It is represented by three numbers, such as the most common 5-10-5. *Note: What these numbers represent are: nitrogen-phosphorus-potassium. Early fall fertilizers should be a 20-8-8 formula, while a late fall fertilizer application might require 13-25-12 mixture.
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.
“Nitrogen applied in the fall is the most important lawn fertilization of the year,” says Robert Cox, Colorado Sate University Cooperative Extension Agent. “Use a high-nitrogen fertilizer, such as 25-5-5, or something with a similar formula.”
Treat weeds and feed your lawn with Scotts® Turf Builder® WinterGuard® Fall Weed & Feed3 in the fall for a better lawn next spring. This weed killer plus lawn fertilizer controls over 50 listed lawn weeds, including clover, dandelion, plantain, morningglory, chicory, eveningprimrose, and purslane.
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.
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.
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 ...
Fall Fertilizer Timing
For the majority of cool-season lawn owners, apply fertilizer anywhere from September through early November. The further north you garden, the sooner you'll feed your lawn. Fine-tune the timing for your locale by talking with your local extension service or garden center.
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.
Apply a nitrogen-rich fertilizer.
If you want your lawn to look better and be healthier, fertilize in the fall.
The theory behind late fall nitrogen fertilization of cool season grasses is very simple. Apply low rates of N fertilizer (40 to 50 lbs/acre) in the late fall (mid October to late November) when cool temperatures have reduced top growth, but root growth is still active.
It's preferred that a quick release fertilizer be used in the fall on turf so that the turf is able to pick up the nutrients quickly before it enters fall dormancy.
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.
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.
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.
Fall is the best time. The autumn season comes with a mix of warm soil and cool air, perfect for planting grass seed and allowing time for new grass roots to develop before winter sets in. It is also a good time to fertilize to build stronger, deeper roots for winter, resulting in a thicker, greener lawn next spring.
Ideal Time to Fertilize
Applying fertilizer (and water) in the afternoon will cause the moisture in the soil that is preventing the lawn from burning to evaporate as the sun beats down on the lawn. It's also important for grass to dry out slightly before the nighttime temperatures.
Don't fertilize during a drought.
Most fertilizers need a thorough watering or two to soak into the soil, and allowing the fertilizer to sit on top of the lawn without watering it in could burn the grass. You may want to delay the application until wet weather arrives.
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.
Tips for applying granulated fertilizer
Always wash fertilizer granules off of foliage. Activate the granulated fertilizer by watering it in right after applying.
If your lawn does need to be mowed and watered, make sure you schedule it for early in the day to avoid moisture evaporation and problems with disease. Don't water your grass before mowing. Wet grass tends to clump together on the lawn which could suffocate the grass underneath or promote fungal growth.
Fertilize during the spring and fall. For cool-season grasses, only minimum amounts of nitrogen should be applied in the summer. Potassium is more important than nitrogen for shaded lawns and it should be maximized as it makes turf more tolerant to shade.
Be sure to mow your lawn the day before applying the top dressing and rake up and remove any debris to allow the nutrients to effectively penetrate into the soil.