Clean Lake Tip – Don't "P" on Your Lawn

“P” stands for phosphorus. It’s a naturally-occurring element, that when present in excess, disrupts critical ecosystem functions and can cause cyanobacteria blooms. It’s carried into the lake through a host of sources, including the runoff from lawns and gardens. According to the 2018 State of the Lake and Ecosystem Indicators Report, phosphorus from developed lands accounts for approximately 16% of the total phosphorus load to Lake Champlain each year. Everyone can take action to reduce phosphorus inputs. An easy way for homeowners to play a part is by avoiding use of phosphorus-based lawn fertilizers.

Most lawns in the northeast have enough phosphorus. If you apply the nutrient when it’s not needed, the excess ends up in our waterways. LCC successfully advocated for New York and Vermont bans on phosphorus in lawn fertilizer, which went into effect in 2012. Exceptions to the laws include: new lawns, lawns that have a phosphorus deficiency (indicated by soil tests), and non-agricultural turf within the first growing season (in New York only).

LCC is a founding partner of Lawn to Lake, a collaborative program promoting healthy lawn and landscape practices in the Lake Champlain Basin. Here are some tips to care for your lawn while also caring for the lake:

1. Use only phosphorus-free fertilizers—look for the zero

The three numbers on a fertilizer bag indicate the nutrient percentages of nitrogen, phosphorus, and potassium (N-P-K) in that order. A zero in the middle means it’s phosphorus-free; for example, 22-0-15.

2. Take a soil test—learn about your lawn

A soil test can tell you about the nutrient levels, organic content, and pH (the soil’s acidity or alkalinity) of your lawn or garden area and what you need for healthy plant growth. In Vermont, The University of Vermont Agricultural and Environmental Testing Lab offers soil testing. In New York, the Cornell Nutrient Analysis Laboratory provides soil testing. The NY lab is temporarily closed due to COVID-19, but they expect to reopen in the coming weeks; they’ll post a notice on their website and social media accounts with updates. Analysis can take six to eight weeks, so May and June are good times to send in samples!

3. Fertilize once a year—apply in the early fall, not the spring

The application of fertilizer in the early fall helps grass survive the winter and prepares it for successful growth the following spring. The best time to fertilize in our region is around Labor Day.

4. Mow higher—raise the blade

Maintain a grass height of three to four inches and cut off no more than 1/3 of the blade height during each mowing. Leave grass clippings on your lawn to build nutrient and organic matter.

5. Water less—grass is hardy

Grass will survive drought conditions without watering by going dormant. Water in the early morning, when the air temperature is cooler, and only when it rains less than one inch during the week.

6. A friendly flower reminder—“weeds” can be beneficial

Flowers like common dandelion, violets, and white clover offer numerous benefits: dandelions and violets provide food to pollinators and clover roots contain nitrogen-fixing bacteria—a natural way to fertilize your lawn, if it’s lacking nitrogen.