Keeping your lawn vibrant and green can be a point of pride for some Florida homeowners — but some of the nutrients in fertilizers used on yards can make local waterways green too.
A seasonal fertilizer ban went into effect June 1 until Sept. 30 in several Tampa Bay area counties, including Pinellas, Hillsborough, Sarasota, Manatee and Hernando counties.
The bans are limited to fertilizers containing nitrogen and phosphorus, which are commonly used in lawn food. When too much of these nutrients get into local waterways, it can result in what University of South Florida Department of Civil & Environmental Engineering professor Sarina Ergas calls the “green pond scum” you’re probably familiar with: algae blooms.
“(Blooms) need water, they need sunlight and they need nutrients,” Ergas said, “and so if we give them nutrients, they’ll grow."
A big green problem
Too much algae can block sunlight, Ergas said, which can negatively impact seagrass mortality — a primary food source for manatees.
Some forms of algae blooms, like red tide, can also produce respiratory toxins, she said, and “others can be quite toxic to humans and animals.”
Murky waters, bad odors and fish kills can also result from excess fertilizer nutrients in local waterways, Ergas said.
ALSO READ: To alleviate toxic algae, Florida Poly scientists are filtering fertilizer nutrients
According to Michael D'Imperio, the Water Resources Agent for the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Extension Sarasota County, there’s not necessarily anything wrong with algae being present in water.
It’s a natural part of our ecosystem. The problem is when algae has more “food than what it would normally have as a result of human activities,” D'Imperio said.
“Once you have a whole lot of additional nutrients in a system,” he said, “that algae essentially is given an all-you-can-eat buffet.”
A fertilizer ban during some of Florida’s rainiest months is a way to control how many extra nutrients get into local waterways, D'Imperio said. Most plant food doesn’t have the chance to absorb into its intended target before summer showers wash it away, he said.
Taking on a sea of a problem
The rainy season fertilizer ban has ranged in the years it’s been in place locally. Pinellas County created a fertilizer ordinance in 2010. Hillsborough County added a summer fertilizer ban to its current rules in 2021. In Manatee County, the fertilizer ban has been in place for over a decade, and the county’s Natural Resources department said it’s made a difference.
Controlling how much fertilizer gets into the water is just “one tool in the tool box,” according to Manatee County's Environmental Protection Division Manager Alissa Powers, but it’s an important and easy one to use. Everyone from homeowners to golf courses can control how much fertilizer they apply to their yards, she said.
Charlie Hunsicker, the county’s director of Natural Resources, added that though the department can’t know whether every resident of the county is following the ban, the department works to educate people so they know not to apply certain fertilizers during this team.
Teaching landscape companies and the public about these rules has had the biggest impact, Hunsicker said. “It’s a big job” making sure all of the county’s hundreds of lawn care companies got the memo on fertilizer restrictions, he said.
After issuing warnings first, he said they rarely need to issue $500 fines, which is what most other Tampa Bay area counties issue for violating the fertilizer ban.
“We can continue to expect a red tide to come ashore. We can continue to expect blooms to happen from time to time,” Hunsicker said. “What these measures can do is reduce the severity of when they occur and the frequency they occur.”
Keeping a nice lawn
There are alternatives for anyone looking to green up their lawn this summer. Michael Masucci, the UF/IFAS Extension Hillsborough County program coordinator, said switching to fertilizers with micronutrients can be a sustainable swap during the ban.
Fertilizers with micronutrients like iron can help your lawn without causing the same top growth that nitrogen and phosphorus, which are macronutrients, do.
Ergas said planting native Florida vegetation that thrives without fertilizers is another option. Homeowners can also test a yard’s soil to see if fertilizer is required at all, she said.
Don Rainey, a UF/IFAS regional specialized water agent, said homeowners have a greater responsibility to protect Florida’s water resources because of the state’s population growth and development.
Conventional stormwater structures are engineered to move water quickly from homes to prevent flooding, he said, and in turn increases runoff draining into larger bodies of water. These structures aren’t made to filter runoff water as it enters the drain, he said, and can be overloaded by misapplied fertilizers and even by grass clippings.
There’s also an economic interest in keeping local water bodies clean, Rainey said. The Tampa Bay area relies on tourists coming down to see “these pristine waterways,” he said.
Even if you don’t live by the coast and see fish kills or algae blooms, he said, your practices while in a region where your water runoff ends up in the bay can add up in impacting water quality.
“It’s exponential if you have a thousand lawns within one community and they’re all fertilizing,” Rainey said. “Then it could produce this cumulative effect, which would impact our watershed overall.”
