If you are anything like me, my social media has been targeting ads for fall lawn fertilizing. Apparently, certain algorithms haven’t figured out that I am not a fan of lawns. I realized there are probably a lot of folks in Anne Arundel County, and around the Bay watershed, who are inundated with this kind of marketing. With that in mind, I wanted to remind folks of some best practices around lawn fertilization that can go a long way this fall and throughout the year.
Impact of fertilizer on the Chesapeake Bay
There is a direct correlation between over use of lawn products and the health of the Chesapeake Bay. In cases where there is overuse, during the next rainstorm, those chemicals and nutrients wash off, into our waterways and cause a dense growth of algae. Once the excess nutrients are consumed, algae and plant life run out of food and die. The decomposition of the plants pulls oxygen out of the water, killing aquatic life.
Is fertilizing necessary?
A soil test can be a great place to start. This resource from the University of Maryland Extension Office details how to sample the soil beneath your lawn and send it to regional soil testing labs. This service costs between $9-$20 and tests for soil pH (acidity/alkalinity), calcium, phosphate, potassium, and magnesium levels. Keep in mind that these tests don’t measure for nitrogen, as nitrogen moves through the soil and quickly changes forms. For lawns, it is best to run this test every 3-4 years in the fall to see how your soil is progressing.
Once you have your soil test, give the soil what it needs and no more. Water-soluble fertilizers come in many different varieties and compositions, so match the needs of your lawn. Lawn maintenance fertilizers have zero phosphorus in them and contain at least 20% slow-release nitrogen. Specialty products containing phosphorus are still available and may be used when a soil test indicates the need for phosphorus. For the typically homeowner, applying a slow release fertilizer is best.
The best time to fertilize cool-season grasses like tall fescue is during the “SON” months, September, October, and November. Keep in mind, in Maryland, fertilizers legally cannot be applied after November 15th. Warm-season grasses like zoysia should be fertilized in the late spring into summer. UMD Extension has a great lawn fertilizer schedule with recommended times which you can see here.
Fertilizer best practices
Do not fertilize:
If heavy rain is predicted or the ground is frozen
Hard surfaces such as sidewalks or driveways
Within 10 to 15 feet of waterways
Between November 16 and March 1
Maryland's lawn fertilizer law helps protect the Chesapeake Bay.
Maryland passed the Maryland Lawn Fertilizer law in 2011 to help curtail overuse of fertilizers. Lawn fertilizer now accounts for approximately 44 percent of the fertilizer sold in Maryland. Knowing what improper use can do, it makes sense that it is regulated to protect our waterways. This law applies to commercial lawn businesses AND homeowners. A major takeaway is when it is legal to fertilize. Your last lawn fertilizer application for the season should be made no later than November 15th in the fall. A spring application cannot be applied until after March 1st. You can read more about this law here.
Alternatives to fertilizing
Overseed and aerate your lawns, especially in situations where turf is less dense. Aeration relieves soil compaction around turf’s roots and allows for better absorption of water and nutrients. Like any other plant, choosing the right plant (in this case grass) for your home’s situation is key. Here is a link to the UMD Extension’s recommendations on choosing the appropriate type of grass seed for your home.
Sourcing this seed is similar to other landscape plants. Grass seed labeled as 'Maryland Certified Seed' (tested for germination and purity by the Maryland Department of Agriculture) is available in select locations such as garden centers, turf supply stores, specialty seed suppliers, or farm supply stores and typically contains UMD recommended cultivars. If MD Certified Seed cannot be located, look carefully on seed tags for the type of grass, variety, percentage of weed seeds, and percentage of noxious weeds.
Consider native alternatives to traditional turf grasses, especially if your home has extreme conditions. Consider low-growing native alternatives like Carex pennsylvanica for shady, dry areas or Bouteloua dactyloides (Buffalograss) for full sun.
Mow it high. Taller grasses help prevent weeds and lead to stronger, deeper root systems which helps reduce runoff and stay greener during drier spells. A height of 2 ½ to 3 inches is ideal.
Water thoughtfully, if at all. Overwatering grass can lead to disease. Remember that cool-season grasses are meant to go dormant in the summertime, leading to their blades turning brown. This time of year, it is more than likely unnecessary to water your lawns, unless you are overseeding and trying to get it to germinate. In that case, follow the directions on your grass seed bag and be as frugal as you can.
Convert your lawn to something a little more natural and forgo the fertilizers altogether! Converting lawns to conservation landscapes filled with native plants leads to lower costs and lower maintenance when compared to typical lawn care. It also aids the local ecology and reduces stormwater. Sometimes the grass isn’t always greener!
Additional resources
Soil testing information from the Maryland Department of Agriculture
Soil Testing and Soil Testing Labs from the University of Maryland Extension Office
Lawn fertilizer schedule chart from the University of Maryland Extension Office
Maryland’s Fertilizer Lawn Law from Maryland Department of Agriculture
Written by Josh Clark, WSA Restoration Coordinator, MLA, CBLP-D, CBLP-I