Spring appears to be on schedule for most of Maryland as temperatures are slowly creeping up into the 50’s and 60’s for highs. One of the temptations for homeowners is to fertilize the lawn “to get the grass going” in the spring. Keep in mind that “spring green-up” is largely related to soil temperatures and, to some degree, whether fertilizer was applied in the fall. Fertilizing with the goal of getting the grass to “wake up” sooner will have a minimal effect since soil temperature is the main driver for this.
Also, keep in mind that fertilizing in the spring favors more shoot and leaf growth at the expense of root growth. (Fertilizing in the fall tends to favor root growth. Most of the fertilizing for the year should be done in the fall.) Spring fertilization should consist of ~1 lb. nitrogen/1000 sq. ft. total in spring. Using a slow-release fertilizer or splitting applications into two 1/2 lb. rates spaced about one month apart should help to limit excessive growth that could add to the increased mowing frequency often necessary in the spring.
Moss is a big issue for some people this time of year and the Home and Garden Information Center has been getting a lot of questions about it. While iron can be applied to slowly “burn off” the moss by layers, mechanical removal with a hard rake or shovel is just as effective and quicker. When moss is present this is an indication of one or more underlying factors relating to cultural maintenance or site conditions. Moss is often associated with low pH (acidic) conditions, shade, wet areas, low fertility conditions, and, often, some combination of these. Just removing the moss will help the “symptom” for a short time, but to keep it away, these underlying issues need to be addressed.
Another rite of spring for many homeowners is applying a crabgrass pre-emergent. Many homeowners apply this product believing it will be a “cure all,” but mowing taller and using a balanced fertility program (~2.7 lb. nitrogen/1000 sq. ft. for cool-season lawns) go a long way to reducing crabgrass as well. Studies have shown that you can greatly reduce the potential for crabgrass invasion just by mowing a little bit higher (3 ½” for tall fescue).
Pre-emergents are typically applied prior to crabgrass germination (look for forsythia to be fully in flower) and then again ~8 weeks later as the products are broken down by temperature and water. Keep in mind that if you have areas that are thin and in need of overseeding that most crabgrass pre-emergent products will prevent desirable seed from germinating too.
Overseeding can be done in the spring but is best done in the fall. If you are overseeding to fill in bare/thin areas this spring, right now in late March/early April is your best chance to get tall fescue established before temperatures warm-up and crabgrass starts to germinate. With last year’s wet summer and fall, we saw crabgrass pressure hold on longer than usual in the Mid-Atlantic. Hopefully, we won’t see a repeat of that in 2019!
Another spring lawn care activity is applying a broadleaf herbicide to weeds. “Spot spraying” broadleaf weeds while they are still young and the weather is mild in the spring can be an effective control technique, but remember, many flowering plants in the garden have some sensitivity to broadleaf weed killers. Always be sure to follow product label directions and take special care around landscape plants.
Cheers to Spring!
By Geoff Rinehart, Lecturer, Turfgrass Management, Institute of Applied Agriculture, University of Maryland.