Lawn Fertilizer Guide for Homeowners & Residents

Everyone is required to obey fertilizer application​ restrictions, use best management practices when applying fertilizer, observe fertilizer blackout dates, and follow University of Maryland recommendations when fertilizing lawns. 

Follow the guidance below to keep your lawn healthy while protecting the Chesapeake Bay from excess fertilizer.

If you're applying fertilizer yourself...​ 

• Follow Un​iversity of Maryland fertilizer recommendations​.
• A single fertilizer application may not exceed 0.9-pound total N per 1,000 sq ft which can include no more than 0.7 pound of soluble N per 1,000 sq ft.
• Phosphorus may only be applied when a soil test indicates that it is needed or when a lawn is being established, patched or renovated.
• Don't use fertilizer to de-ice walkways and driveways.
• Clean up fertilizer spills.
• Keep fertilizer10 to 15 feet from waterways.
• Do not fertilize lawns if heavy rain is predicted or the ground is frozen.
• Do not apply lawn fertilizer between November 16 and March 1.
• ​Enhanced efficiency controlled release products may be applied at no more than 2.5 pounds per year, with a maximum monthly release rate of 0.7 pound of N per 1,000 sq ft.

Buying fertilizer

Calculate the area of your lawn to determine how much fertilizer to buy. Do not buy more fertilizer than you need and always read and follow label instructions. 

To calculate your lawn’s square footage, multiply your lawn’s length by its width.  Next, subtract the areas not to be fertilized such as the house, deck, driveway and garden. The remaining area is the square footage of your lawn.

How to read a fertilizer label

All fertilizer products are labeled with three numbers separated by dashes that represent the percent by weight of the three most important plant nutrients: 

• Nitrogen (N) — Promotes green, leafy growth 
• Phosphorus (P) — Promotes root, fruit and flower development 
• Potassium (K) — Promotes disease and drought tolerance 

These numbers are always displayed in the same order. A 17 lb bag of 27-0-5 fertilizer contains 27 percent N, 0 percent P (as required by Maryland law) and 5 percent K.

The weight of the fertilizer bag and the amount of area covered by the product are listed on the fertilizer label. Look for this information so that you will know how much fertilizer to buy. 

How to apply fertilizer properly

Never apply fertilizer by hand. 

Use a drop or rotary spreader to apply fertilizer evenly to your lawn and always keep fertilizer applications 10 to 15 feet from waterways. To prevent striping, overlap wheel tracks of the drop spreader. Spread half of the fertilizer in a north-south direction and the other half in an east-west direction. Always check the fertilizer product for recommended spreader settings.

If you hire a lawn care service... 

Individuals and businesses that hire lawn care providers should confirm that professionals are certified and licensed by the Maryland Department of Agriculture. Learn more about how to select a lawn care service.

Fertilize at the right time 

To prevent runoff, fertilizer should only be applied to lawns when the grass is actively growing. Fertilize warm season grasses (Bermudagrass and Zoysiagrass) in late spring or summer and cool season grasses (fescues, bluegrass) in fall, based on soil test results. Do not exceed single and yearly application limits. 

Tips for a healthy lawn

There are many things you can do to maintain and enhance the health and beauty of lawns while limiting environmental impacts. Here are a few tips: 

Mow to the right height 

Mowing lawns to the proper height can reduce weed problems by as much as 80 percent. Low and infrequent mowing can damage your lawn as well. Remove no more than 1/3 of the grass height each time you mow.

Keep lawnmower blades sharp

Have your lawnmower blade sharpened each spring. A dull blade can damage grass and increase the likelihood of disease.

Let lawns go dormant

Some grass species have natural dormancy periods and will turn brown during the hot, dry summer months. Applying fertilizer to force a lawn to turn green during its dormancy period can damage the grass. It is also unnecessary to water grass that has gone dormant. Dormancy is a natural survival mechanism and lawns usually recover when the rains return. 

If you must water your lawn, (and watering of grass is not prohibited because of drought conditions), do so early in the day using a sprinkler. As a rule, water less often for longer lengths of time. Avoid frequent, light watering—it promotes shallow root growth and encourages weeds.  

Aerate the soil

Water, air and nutrients needed by grass roots cannot penetrate soils that are compressed, compacted or have a high clay content. Aerate the soil to reduce compaction and allow grass roots to strengthen and grow. Lawn care professionals can provide this service or you can rent a sod core aerator from a lawn and garden supplier.

Recycle grass clippings

Grass clippings are a free source of nutrients and will not cause thatch problems as long as the grass is not allowed to get too long before mowing. If clippings are too long, they may clump. Rake up excessive clippings for mulch or compost and mow more frequently. Sweep or blow grass clippings and other lawn debris away from street gutters. Grasscycling can reduce your lawn’s nitrogen requirement by as much as 50 percent.