Hello pdaly52305,

Here’s a clear, research‑based answer grounded in university extension guidance — exactly what you’d expect from a “site:edu” search.

A Good Basic Fertilizer for a Michigan Lawn

If your lawn hasn’t been fertilized much over the years, the safest and most broadly recommended starting point from university extension sources is:

️ A slow‑release, complete fertilizer with an N‑P‑K ratio similar to 20‑5‑15 or 24‑4‑8

These ratios are commonly recommended because they supply nitrogen (N) for growth, a modest amount of phosphorus (P) for root development, and potassium (K) for stress tolerance. More information at this link:

Fertilizing Home Lawns to Protect Water Quality - MSU Extension

Why this works well:

Nitrogen drives green color and density.

Phosphorus supports root growth (especially helpful for neglected lawns).

Potassium improves disease resistance and winter hardiness — important in Michigan.

Slow‑release nitrogen prevents rapid, weak growth and reduces runoff risk. More information at this link:

Fertilizer Selection | University of Michigan-Dearborn

Michigan State University Extension and the University of Michigan–Dearborn both emphasize choosing a slow‑release fertilizer as one of the most important decisions you can make.

Before You Buy: Consider a Soil Test

MSU Extension strongly recommends soil testing to fine‑tune your fertilizer choice, especially because Michigan soils vary widely in pH and nutrient levels. More information at this link:

Soil testing through MSU Extension - Managing Soil Health

A test can tell you:

Whether you actually need phosphorus

Whether potassium is low

Whether pH adjustments are needed

But if you want a good basic fertilizer without testing first, a slow‑release complete fertilizer in the ranges above is a safe, research‑supported starting point.

When to Apply in Michigan

MSU Extension advises waiting until May for the first application — not early spring — to avoid stimulating excessive top growth before roots are ready. More information at this link:

When should I fertilize my lawn during spring? - Gardening in Michigan

If You Want a Simple Plan

Here’s a straightforward, university‑aligned approach:

May: Apply a slow‑release fertilizer (e.g., 20‑5‑15 or 24‑4‑8).

Late June/July: Optional light feeding if the lawn is irrigated. 

Early September: Another slow‑release application — often the most important of the year.

Late October: Optional final application for winter hardiness.

Most extension programs recommend 2–4 lbs of nitrogen per 1,000 sq ft per year, spread across 2–4 applications. More information at this link:

Fertilizer Selection | University of Michigan-Dearborn

I hope this helps!