For those of us who are lucky enough to have one, maintaining a thriving yard takes work—a lot of it. That’s why the idea of fertilizing with the most powerful stuff as often as you can may sound pretty appealing. Trouble is, no one-size-fits-all solution exists for fertilizing your outdoor space. Fortunately, doing some homework will put your lawn—and Mother Earth—in a winning position.
First things first: Know thy dirt. The best way to assess your fertilizer needs is to do a soil test to measure things like acidity and composition. It’s a bit of a process, yes, but it’ll enable you to really know what you need to make your garden thrive. The University of Illinois Extension has some useful resources on this, including a list of soil test labs around the state that can handle this for you, as well as tips on how to prep the soil sample. Prefer to do it yourself? Check out these tips from the DIY Network, and pick up a soil test kit from a local hardware or gardening supply store.
Once you’ve got that done, this more intimate portrait of your soil will help you choose the best ratio of nutrients—Nitrogen (N) to Phosphorus (P) to Potassium/Potash (K)—a decision that can make or break not only the health of your plant, but also the well-being of our waterways as well.
How’s that? Well, as you may know, N and P overages are largely responsible for many of our nation’s polluted waters, including Lake Michigan and the Chicago River. A quick chemistry 101 check reminds you that these nutrients are necessary for plant development, both on land and in the water. But when they show up in excessive quantities in the water, they lead to overgrowth of algal blooms, which sucks the oxygen out of water to create areas where no other life can form, aka dead zones. That makes the water ugly, smelly, and toxic. Not too cool considering so much of the nutrient overload is preventable.
Oftentimes, the soil in an urban area like Chicago already has pretty decent levels of nitrogen in it. Plus, already-established plant life needs far less of it than newly seeded things. And yet, many people use P-heavy fertilizer unnecessarily, simply because they don’t know they don’t need it. That’s why 11 states—including Illinois—have passed legislation either limiting or straight-out banning the use of P in fertilizers.
Head spinning? We hear ya. Here are some quick fertilizing tips to keep in mind once you’ve done your trusty soil test:
- Time it right: If necessary, it’s best to apply nutrients in spring, fall, or both, when roots are actively growing. Avoid doing so during drought or when the ground is frozen, and before heavy rainfalls.
- Contain it: Keep fertilizer off paved areas, to prevent as much runoff as possible.
- Read the label: Buy fertilizer with low or no P, depending on your soil test results. (Easy peasy, since fertilizers are required to show the NPK ratio.)
- Don’t overdo it: You may not need to fertilize anywhere near as much as you think you do—in fact, you might not need to do it at all. Again, the soil test results will help you make this decision.
- Go organic and P-free: When it is time to fertilize, consider going for the best of both worlds. A couple of organic, P-free options include McGeary Organics Low Phosphorus Fertilizer and Turf Nurture 15-0-7 Low Phosphorus Fertilizer. Pssst: this is not a case where organic trumps all—because they’re usually byproducts of animal manure, organic fertilizer tends to have high P levels. So, again just check the label first.
Of course, there’s a lot more info where that came from…For more eco-friendly (and successful) fertilizer tips, check out these other resources:
- The Environmental Protection Agency
- University of Illinois Extension
- Purdue’s Fertilizer Calculator
- The Informed Gardener