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Q: I usually fertilize my lawn in July when everything is growing, but my neighbor said summer is the wrong time to fertilize grass. Which one of us is right?
-- Chuck from Boardman
A: In this case your neighbor is right. Summer just isn't the best time to fertilize turfgrass. Almost all turfgrasses in northeast Ohio are cool-season grasses. These grasses include bluegrasses, fescues and perennial rye. These varieties grow best when the weather is cooler in the spring, and fall and grow slowly or go dormant during hot summer weather. Fertilizing the lawn in summer will not benefit the turfgrass but may help any weeds in your lawn.
Most weeds found in turfgrass like the weather warmer. And speaking of hot weather, when mowing the lawn when it's hot and dry raise the height on your mower deck. This will help your lawn stay healthy and conserve moisture.
The best time to fertilize cool-season turfgrass is in the fall. If you fertilize the lawn only once a year, then fall is the time to do it. Fall fertilizer helps the grass recover from summer conditions and promotes root growth to make the grass come back thicker next spring.
Fall is the best time to fertilize, but studies by Perdue show that several fertilizations during the year will promote a stronger, healthier lawn than just one application. And a strong healthy lawn is the best defense against lawn weeds. Fertilize once or twice in the spring and two or more times in the fall.
Research by Ohio State shows that a late November fertilizer application is a good time to promote strong grass root growth. Don't fertilize the lawn during winter.
Why are several fertilizer applications better than one? Turfgrass, like all plants, needs all three of the primary nutrients, nitrogen, phosphorus and potassium, to grow and stay healthy. The primary nutrients are those listed on fertilizer products as numbers in the form of N-P-K. Of these three, nitrogen is the most important nutrient for turfgrass. But nitrogen doesn't last in the soil like phosphorus and potassium do. It must be replenished to be available when the grass needs it.
Several fertilizer applications at the right times keep the Nitrogen available in the soil.
So how much fertilizer do you need to apply? The only way to know is with a soil fertility test and the best soil tests are laboratory tests. Soils should be tested every two to three years. A complete lab fertility test will show what fertilizer, other than Nitrogen, is needed as well as other important information about your soil.
Adding fertilizer, or other soil amendments, without knowing if they are needed is a waste of money and can harm the environment. Fertilizer runoff is a main cause of algal blooms in ponds and lakes.
Look online to find laboratories offering soil fertility tests. The Mahoning County Extension Offices offers complete lab soil fertility tests. The extension office can also tell you the best way to take soil samples for testing. If you get a soil test via the extension office, you get an experienced staff member or master gardener to go over the test results with you if you have any questions. Call 330 533-5538 for information on soil tests.
For more information see: http://go.osu.edu/feedlawns
David Sprague is an OSU Extension Master Gardener Volunteer in Mahoning County. The plant and pest clinic is open Mondays and Thursdays from 9 a.m. to noon at the OSU Extension Office in Canfield. Details at http://go.osu.edu/mahoningclinic