Bay-Friendly Tip: If you’re going to fertilize, do it before mid-October

Bay-Friendly Tip: If you’re going to fertilize, do it before mid-October

Mackensie duPont Crowley, content & digital media specialist

Did you know that during periods of drought or extreme temperatures, your lawn goes dormant in order to conserve water and nutrients? During this time, your grass is still alive but is not actively growing. Once temperatures become more ideal and a regular water supply is available again, your lawn should return to its green color! This growth typically begins before you first start to visibly notice a difference in your lawn, starting at the grassroots beneath the ground surface

Any added fertilizer will limit the amount of root development by redirecting all efforts into blade growth. As a result, fertilizer should only be added to your lawn in the fall, before mid-October, or in late May or June when you notice that your lawn is starting to turn green and grow on its own.

How does fertilizer harm Narragansett Bay?

Excess nutrients in many store-bought fertilizers contribute to water pollution in Narragansett Bay and its watershed. Rainfall or overwatering can lead to any added nutrients or fertilizers running off of your lawn, onto the pavement, and into nearby storm drains and eventually the Bay. These excess nutrients negatively affect water quality, resulting in algae blooms and fish kills. 

What Can You Do This Fall to Ensure A Healthy, Bay-Friendly Lawn?
  • Many people choose not to fertilize their lawns at all! 

    Fall leaves on a green lawn
    Shredded leaves break down over the winter and serve as fertilizer for your yard. A leaf cover of up to 6 inches thick can be mowed in one pass, depending on the capabilities of your mower. Small leaf pieces will remain and filter down through the turf to rest near the base of your grass within a few days.
  • Mulch your leaves. Several studies, such as those conducted by the University of Minnesota and Michigan State University, have shown that mulching leaves in place can help improve lawn quality when it is revived in spring. The leaves of some deciduous trees, such as the honey locust, can add important nutrients like nitrogen to the lawn, while leaves from other trees, such as maple trees, can inhibit weed growth and add phosphorus.
  • Utilize other Bay-friendly alternatives as fertilizer. Grass clippings can be left on your lawn after it has been mowed, which will provide up to one-third of your lawn’s nutrient needs for free. Alternatively, you can add up to 0.5” of compost to your lawn or garden. Compost is nutrient-rich organic matter produced by bacteria and worms that break down food scraps and garden waste, and it will restore vitality to depleted soil!
  • If you do fertilize with store-bought fertilizer, take these precautions. 
    • Test the pH of your soil before adding fertilizer. If the pH of your lawn is too low, the grass will not be able to absorb the fertilizer.
    • Never fertilize immediately before or after rainfall. 
    • Choose slow-release fertilizers that release nutrients gradually over time, making it less likely that excess nutrients will be washed off of your lawn and end up in the Bay. 
    • Fertilize sparingly, during ideal times (in spring after your lawn greens up, and/or in fall before mid-October).

To learn more about fertilizer and its effects on a watershed, listen to this Public’s Radio podcast episode featuring our director of habitat restoration, Wenley Ferguson.

For more Bay-friendly tips, download our Bay-Friendly Living Guide!