I try to base this column on the questions that come in to the Extension Office each week, and right now, fertilizing lawns is a hot topic. I have talked about some of the basic principles of lawn care before, but today I have a new spin on fertilization based on the concepts of a new program called Green Yards and Communities. You will hear more about this program in the weeks to come.
Applying fertilizer when it is most useful to the plant is the most important thing to remember. The Environmental Protection Agency reports that more than 70 million tons of fertilizers are applied to residential lawns and gardens annually - and much of it is unnecessary, so get the facts on what you need before you apply.
Lawns are purposeful in the landscape. Turfgrass filters stormwater runoff and prevents erosion by holding soil with plant roots. My lawn holds the soil on a steep bank in my yard better than most ornamental plants could - and requires less weeding.
Fescue is the most common grass species used in this area and the best choice of cool-season grasses, and the following management recommendations will refer to it.
Q: When should you fertilize?
A: Apply fertilizer to fescue only in September and November for best results. You may make a third application in May only if your lawn is irrigated. Research proves that fescue lawns require a maximum of three fertilizer applications to stay green and healthy.
Fertilizing now (in the spring) encourages lush growth that the roots will not be able to support later this summer, so you will end up watering more. Improperly fertilized lawns also develop more thatch (compressed surface roots, stems and runners between grass blades and soil) which can keep water and nutrients from reaching plant roots.
If you want to fertilize less than three times a year, September is the prime time for application.
Q: What kind and how much fertilizer does your grass need?
A: The three numbers on the bag represent nitrogen (N), phosphorus (P) and potassium (K), respectively. All plants require these nutrients (and several others) to survive, but many of them are available in the soil, air and water. Nitrogen is the most common nutrient that needs replacement because plants use more of it than any of the others.
All fertilization programs should be built around nitrogen requirements. Fescue only needs 1 to 1 1/2 pounds of nitrogen per 1,000 square feet to be healthy. Add phosphorus and potassium only if needed. Excess nutrients make it harder for the plant to use other nutrients and can also run off of the lawn into stormwater and eventually into our water supply.
The only way to know for sure how much phosphorus and potassium your lawn needs is to have a soil test. Kansas State University has a laboratory that performs the analyses, and samples can be submitted through the Douglas County K-State Research and Extension Office (or your local county's office). Douglas County residents can test up to 10 samples free of charge because of a temporary grant partnership with the Douglas County Conservation District.
Soil from vegetable and flower gardens and landscaped areas can also be submitted for nutrient analysis.
Make some changes in the way you fertilize your lawn this year for the good of your yard and your community. To me, saving money on unnecessary fertilizer means I have more to spend on flowers and shrubs for my landscape.
Stay tuned for more information about Green Yards and Communities. If you have gardening questions, call a Douglas County Extension Master Gardener at 843-7058, 1 p.m.-4 p.m. Monday-Friday, or e-mail firstname.lastname@example.org anytime.