Late fall is one of the best times to apply lawn fertilizer: Here's how
Many gardeners and homeowners have completed their fall gardening and home landscape maintenance tasks for the season once the final leaves are removed from the lawn sometime in November, but they may overlook a critical lawn maintenance task that will help their lawn survive the winter and thrive early next spring. By mid- to late November, growth of lawn grasses slow considerably, and many homeowners eagerly look forward to putting the lawn mower away for the season after mowing the lawn for the final time.
As soon as you put the lawn mower away for winter this month, be sure to get out the fertilizer spreader so you can make the final lawn fertilizer application of the season. While most gardeners and homeowners only think about applying fertilizer to their lawns in the spring, late fall is one of the best times of the year to improve a stand of lawn grass, when a small investment of time and fertilizer will yield a healthier, greener and denser stand of turf earlier next spring.
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Late fall critical time for turf grasses
Fall is the time when cool season grasses recover from summer stresses such as drought, heat and disease, and is also the time when turf grasses begin to store carbohydrate reserves in the stems and rhizomes. These carbohydrate reserves help grass plants fight winter injury and disease and, more importantly, serve as a source of energy for root and shoot growth the following spring. Late fall fertilization will provide better winter color of the stand, quicker green-up in the early spring, and an increase in root growth. Late fall applications of fertilizer are more important to the health of lawn grasses than spring applications more commonly practiced by most gardeners and homeowners.
Timing fall fertilizer applications
The best time to make late fall applications of lawn fertilizer is typically in late November or the very beginning of December when the grass stops actively growing or has slowed down to the point of not needing to be mowed. I like to make the last application of lawn fertilizer after I mow the grass for the last time in November and before I get out my outdoor Christmas decorations. Even though the leaves and shoots of the grass plant have stopped actively growing at this point, the roots are still actively growing, allowing the plant to make maximum use of available fertilizer in the soil. Fertilizer applications should never be made once the ground is frozen.
Choosing a fertilizer blend
As a general rule of thumb, 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 in November. The best method for determining exactly how much fertilizer is needed is a soil analysis conducted by a laboratory. It’s not too late to have your soil tested this fall in order to determine exactly how much fertilizer your lawn will need. To have your soil tested, go to: go.osu.edu/franklinsoiltesting.
A complete fertilizer with a high ratio of both nitrogen (N) and potassium (K) is essential for root growth, winter hardiness, and disease resistance. An ideal fall fertilizer blend will have a nitrogen to phosphorous to potassium (N:P:K) ratio of 24-4-12. When shopping for lawn fertilizer, you may find that some fertilizer manufacturers have completely removed phosphorous (P) from some fertilizers due to overuse and the environmental harm caused when excess phosphorous is carried into surface waters such as streams and lakes.
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Fall lawn weed control
November is also an excellent time to control many annual weeds in the lawn. Winter annual weeds such as purple deadnettle, hairy bittercress, henbit and common chickweed are in the small seedling stage right now, and treating them with an herbicide at this growth stage can be an effective method for removing them from the stand in advance of green-up next spring. Other annual weeds such as dandelion, plantain and even clover can also be controlled in late fall when these plants are still actively growing.
Applications of lawn herbicides are best done when the daytime temperatures are 50 degrees Fahrenheit or greater, so be sure to keep an eye on the weather forecast when planning late fall applications. Always use the ester forms of lawn herbicides in the fall as these formulations are more effective than amine forms in cooler weather.
So find that fertilizer spreader in the back of your garden shed and provide some nutrition for your lawn at the time of year when it is most needed—late fall and winter.
Mike Hogan is Extension educator for Agriculture and Natural Resources and associate professor with Ohio State University Extension. hogan.1@osu.edu
This article originally appeared on The Columbus Dispatch: Benefits of late fall lawn fertilization
