Reviewed by: Callie Morrison
Alabama’s beautiful Cahaba Lilies + other reasons not to overfertilize your lawn
Reading time: 5 minutes
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If you’ve ever taken a trip down to Bibb County to see the Cahaba Lilies, you know what a treasure these glorious flowers that bloom each year between Mother’s Day and Father’s Day are.
But did you know that each time we fertilize our yards here in Birmingham, we’re putting those flowers at risk?
We spoke to Margaret Tanner, Deputy Director of Jefferson County Environmental Services, to learn how to protect our waterways and all the life that they support.
1. Rain washes nutrients from fertilizers into waterways
When my kids were little, I loved how excited they got watching torrential rainstorms here in Birmingham drain down into the gutters near our house. But I never really thought about where the water went after that.
According to Tanner, stormwater makes its way to the nearest creek, pond or lake, and from there flows into bigger creeks, streams and rivers.
When you fertilize your lawn, only a portion of what you put on your grass or plants is used. Whether you fertilize appropriately or over-fertilize, thinking that will yield the mini-golf-course look you’re going for, the nutrients mix with rainwater, then end up in our waterways.
2. Aquatic plants + algae use the nutrients from fertilizer to grow
Just like the nutrients from the fertilizer help to make your garden grow, they also help aquatic plants and algae grow. And grow. And grow.
As the green things keep growing and the rain ends, the supply of nutrients dries up and eventually the plants die.
This whole process is called eutrophication. It’s a big problem in almost all large waterways near major urban areas, and it’s a big problem here, too.
Learn more about how to protect our environment. Visit Jefferson County Environmental Services today.
3. When excessive growth runs out of nutrients, it dies + may kill fish
When the algae and aquatic plants die, they create organic matter. The bacteria that eat the decomposing organic matter suck all the oxygen out of the water.
When this happens, fish can die, harming the impressive biodiversity we have in our local waterways.
4. Alabama has placed nutrient limits on rivers
Luckily, to address this problem, we have nutrient limits on most rivers around the Birmingham area.
The Cahaba, Tombigbee and Black Warrior Rivers all have a total maximum daily load of pollutants and nutrients that can enter the waterway and still be considered safe for “designated uses.”
Designated uses include fishing, swimming and recreational sports. For a river to be safe for those activities, the portion of nutrients it receives on a daily basis must be small.
5. If you fertilize your lawn, here’s what you can do
Of course, not everyone chooses to fertilize. In fact, here are three popular alternatives:
Before you fertilize at all, check to see if your lawn needs fertilizer.
Here’s how:
- Pick up a soil test bag at Birmingham Botanical Gardens or your local Alabama Cooperative Extension office.
- Send to the Auburn Soil, Forage & Water Testing Laboratory—this costs $10.
- They will process + send you back a report; most of the time, you don’t need fertilizer at all.
- Alternatively, you can order a Soil Test Kit from Auburn University for $29.95.
Check out this podcast to learn more about soil testing.
If you do choose to fertilize, though, no shame. Just take these two important steps to help protect our waterways.
- Don’t over-fertilize: Read the instructions carefully + only use the amount needed.
- Apply fertilizer 20-50 feet back from waterways: The additional ground can absorb the excess nutrients.
6. Protecting the Cahaba River means preserving the Cahaba Lilies
The Cahaba River has an Outstanding Alabama Water segment just south of Birmingham. The idea with this designation is to keep pristine waterways pristine so they can support diverse ecosystems and animal populations.
The Cahaba Lily is a beloved species here in Alabama, and the eutrophication that’s caused by excess nutrients can affect its growth cycle, according to Margaret Tanner with Jefferson County Environmental Services.
By being mindful of how, when and where we use fertilizers, we can help protect these beautiful flowers and the ecosystem that supports them.
Learn more at Jefferson Count Environmental Services today.
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