Spring is here, and that means millions of Americans will soon be seeding, fertilizing and mowing their grass.

America has a lot of lawns. Add them all together, and they’d cover an area roughly the size of Florida, making grass the most common irrigated plant in the country. And all that grass comes with an environmental cost.

To keep weeds at bay, homeowners dumped around 59 million pounds of pesticides onto their residential landscapes in 2012, according to the Environmental Protection Agency. Some of those leach into the waterways, potentially exposing children and pets to harmful chemicals.