There is now an ordinance in Ann Arbor, aimed at protecting the Huron River watershed, prohibiting the use of lawn fertilizers containing phosphorus.* Luckily, Scotts has created a line of zero-phosphate fertilizers for areas like Ann Arbor. You can enjoy the benefits of the same 4 Step program you used in the past, while still protecting the watershed. Pick it up early, because crabgrass will start to germinate if you don't apply Step 1 in March or April. Step 1 prevents crabgrass, Step 2 kills broadleaf weeds, Step 3 fertilizes with 2% iron, and Step 4 prepares the lawn for the winter. Each step, of course, also feeds the lawn with a high-nutrient, slow release fertilizer.
* You can still use phosphorus fertilizers on vegetable and flower beds, and you can use phosphorus lawn fertilizers on new lawns just not existing ones. We still carry Step 1 For Seeding and Starter Fertilizer with phosphorus if you're seeding a new lawn.
For more information, check out the Phosphorus Fertilizer Ordinance section on the website for the City of Ann Arbor.
Scotts 4 Step Zero-Phosphate Lawn Program