When to fertilize your lawn
Timing matters as much as what you use. But instead of just looking at a calendar, look at your grass.
Most people wait for their yard to look hungry, but the secret is feeding it right before or during its peak growth window. This is the time of year when your grass is living its best life and ready to soak up every drop of fertilizer.
When is my lawn’s peak growth window?
It depends on your local ecoregion and whether your grass is cool or warm.
- Cool-season (Northern/Coastal): You’ll see two peaks. One in late spring (think May to mid-June) and a second wind in early fall (late August to September).
- Warm-season (Southern): Your grass is a sun-worshipper. Its power window is mid-summer, usually peaking between July and early August.
Want the exact dates for your specific zip code? Skip the guessing game and let our custom lawn plan map out your peak growth schedule for you.
Sunday map of warm- and cool-season grass regions in the United States.
What are the best conditions to fertilize my lawn?
Dates are just a guide. What’s happening outside your window right now is what actually matters.
It's a great day to fertilize if:
✓ Morning temperatures are between 50–85°F.
✓ Your grass is actively growing (if you’re mowing regularly, it’s eating regularly).
✓ No heavy rain in the forecast for at least 4 hours.
✓ You mowed in the last 2–3 days.
Hold off if:
✗ It’s pushing 85°F or higher.
✗ Your lawn looks brown, crispy, or drought-stressed.
✗ Your grass is still dormant (brown and sleeping).
Sunday Tip:
Fertilizing at the wrong time can burn your lawn or just waste product. When in doubt, waiting is the smarter move. Your grass won't hold it against you.
Get to know your grass type (and region)
Cool-season grasses
Map of Sunday cool-season grass regions in the United States.
Common types include Kentucky bluegrass, fescue, and perennial ryegrass. These guys love a "spring sprint" and a "fall finish." If you only feed them once, make it a fall fertilization—it’s like meal prepping before a long winter nap.
More about cool-season care:
Warm-season grasses
Map of Sunday warm-season grass regions in the United States.
These include bermudagrass, St. Augustinegrass, zoysiagrass, centipedegrass, and bahiagrass. Summer is the main event. This is when your lawn puts those nutrients to work building a thick, green carpet.
More on warm-season care:
At the end of the day, fertilizing isn't about achieving a neon-green chemical perfection.
It’s about supporting the living, breathing ecosystem right outside your back door. When you time your nutrients with your lawn's natural rhythm, you're building a yard that's more resilient and ready for whatever memories you're planning to make on it this year.
Ready to get to work?
Knowing when to go is half the battle. Knowing how to do it without making a mess is the other half. Whether you're a first-timer or a seasoned yard nerd, we’ve got you covered.
- How to Apply Sunday in One Weekend: A step-by-step guide to getting your nutrients down like a pro.
- The Ultimate Lawn Care Calendar: For the folks who want to see the whole year at a glance.
- Environmental Benefits of Lawns: Why all this work matters (for more than just the neighbors' approval).
Take the guesswork out of peak growth.
Our lawn engine uses satellite data to map your lawn and pinpoint your specific peak growth windows based on local rainfall, grass type, and climate.
