Kim Sullivan, Extension Master Gardener in Anoka County
Last fall, we let you know that fall is the best time for lawn care (http://www.anokamastergardeners.org/blog/2016/9/6/falls-the-time-to-love-your-lawn) . With a few important tasks to finish this spring, you’ll have a summer of sun, fun and low-maintenance lawn care.
Most folks start spring with a crabgrass pre-emergent. We’ve already hit the early-optimum soil temperature for that application, but try to hold off until mid-April. Putting it down too early means that in 6 weeks you’ll probably have to add another half-application to make it through the summer.
Don’t use weed and feed products. Pre-emergent crabgrass preventer can go on when the soil is much colder. Fertilizer needs the soil to be warmer. Fertilize too early and it runs off or through the soil. Both products need to be watered in after they are applied.
For spring broadleaf treatment, identify the weed. While it’s still small, hand-pull or spot-treat with an appropriate post-emergent weed killer. Don’t paint your lawn with weed killer. Always read and follow label directions.
Fertilizer has a grade, such as “24-0-12” telling you the percentage of Nitrogen, Phosphorus and Potassium that are in the bag. A grade with a ratio of 4-0-2 is generally adequate for most lawns. If 35 – 50% of the nitrogen is “insoluble” nitrogen, that’s great because it’s slow release. A soil test from the U of M will help you decide if other nutrient additives are needed.
Grass uses additional nitrogen in the fall, putting down its deepest roots and storing energy for the spring. Put down 2/3 of your annual nitrogen application in the fall. Add the last 1/3rd of nitrogen around Memorial Day - that gives the grass enough energy to get through the summer. Many lawns do fine with 3 pounds of nitrogen per year, 2 pounds per 1,000 square feet of lawn in the fall and 1 pound per thousand square feet in the spring. (A 20lb bag of 24-0-12 fertilizer has about 1 lb of nitrogen in 4 lbs of fertilizer. If your lawn is 4,000 sf, use 8 pounds of fertilizer.)
Wait to mow until it’s up, green and growing. For most grass types, 3 – 3.5 inches or taller is good. Take off only 1/3 of the blade at a time. Leave clippings on the lawn to save one fertilizer application per year, keep the soil cooler, and improve the soil.
Water about an inch every 10 days or so. Break yourself of the habit of running the sprinklers every day. Let the soil get fairly dry between watering, but not so dry that the crown (which produces new shoots of grass) dies. Seeing footprints on the lawn when you walk on it is an excellent signal to water.
With crabgrass and other weeds controlled, and lawns fertilized, watered and mowed, you are all set to enjoy the growing season.