Every spring, many homeowners ask themselves, "Should I use fertilizer on my lawn, and if so, how much?" and "What is the right way to control crabgrass?" Virginia Cooperative Extension has research-based answers to questions about spring lawn care.
Mike Goatley, Extension turf specialist, recommends that homeowners determine what nutrients their lawns need before adding fertilizer or other chemicals.
“There is no better money spent than to have a soil test done on the lawn and garden areas at least every third year,” said Goatley, who prepares regular podcasts on lawn-care topics on Extension’s Turf and Garden Tips website. “A soil test is the only way to determine if the soil needs lime, phosphorus, potassium, or other nutrients.”
Most soil tests will not test nitrogen levels because they change rapidly. According to Goatley, cool-season grasses benefit from some nitrogen application before they have the most significant period of root development in the spring. The key to success in spring nitrogen fertilization for cool-season grasses is to use minimal chemical applications for maximal effect – no more than one pound of nitrogen per 1,000 square feet should be applied for the season. Because warm-season grasses initiate most of their root growth later in the year, most homeowners should wait until 50 to 75 percent of a lawn greens before applying nitrogen. “Excessive spring nitrogen fertilization that promotes a lot of shoot growth can be disastrous to the turf if there is a late freeze,” he added.
The Turf and Garden Tips website has details about choosing a nitrogen source, applying the appropriate amount of nitrogen, and mitigating environmental concerns when using fertilizers and other chemicals on a lawn.
In addition, many homeowners wonder how to deal with crabgrass, the most common weed problem for managed turfgrass. Shawn Askew, Extension turfgrass weed specialist, advocates that the lawn itself controls far more weeds than any chemical ever applied.
“A thick, healthy turf is the best method of crabgrass control,” Askew said.
A dense lawn entering the spring growing season will have minimal crabgrass infestation that can be managed with hand pulling. On the other hand, a sparse lawn will almost certainly have a weed problem that requires more inputs to improve turfgrass density and may need preemergent herbicides to control crabgrass.
According to Askew, one option is to apply more grass seed. When applying grass seed in spring, be sure to use special crabgrass herbicides that are safe during turfgrass seedling establishment. If a few crabgrass plants escape your efforts and you are unable or unwilling to hand pull them, postemergent herbicides are available in ready-to-use spray containers. Tackling large infestations of crabgrass plants with postemergent sprays is a job best left to professional lawn-care operators.
“Remember that the label is the law when it comes to pesticides,” Askew added. “This protects you, the environment, and your lawn.”
Your local Extension office can direct you to more information about gardening and lawn-care topics, including soil testing.
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