If you're eager to green up your lawn after winter, you're not alone, but jumping the gun with spring fertilizer can do more harm than good. The first fertilizer application comes down to timing. “[It] depends on location and grass type," shared Maggie Reiter, Lead Scientist at Sunday.
Her advice? Watch your lawn—not the calendar. "I always ask ‘Have you mowed yet?’ The best time to fertilize is when the grass is actively growing and you’ve mowed at least once. This level of growth above ground is when your lawn is ready to uptake nutrients below ground."
Start by Understanding Your Entire Lawn
Lawn care varies depending on what types of grass you’re growing. In the U.S., most lawns fall into two categories: cool-season or warm-season grasses.
Cool-season grass—like Kentucky bluegrass, ryegrass, and fescues—grows best in the northern part of the country. These grasses start growing as temperatures rise in early spring, but that doesn’t mean it’s time to activate your lawn fertilization schedule.
Wait until you’ve mowed once or twice. This shows your lawn is truly awake and can actually use the nutrients. Adding any type of fertilizer too early can feed common weeds or stress your lawn if the natural growth cycle hasn’t fully kicked in.
Warm-season grasses—like Bermuda, zoysia, and St. Augustine—are common in southern areas. This type of grass needs some summer heat to get going. The root structure stays sleepy longer into spring. For these types, hold off for a late spring feeding... or even early summer.
Know Your Region’s Timing
There's no arguing that spring hits differently in Maine than it does in Texas. Local temperatures and soil warmth play a big role in when your lawn starts growing. Here's a general idea of when lawns are usually ready for lawn fertilizer, based on region:
- Northern states (Minnesota, Michigan, Maine, New York, etc.): Late April to early May, after the second mow
- Midwest and Mid-Atlantic (Illinois, Ohio, Virginia): Mid to late April
- Southern states (Georgia, Texas, Florida): Late April to mid-May, depending on soil temps
- West Coast (California, Oregon, Washington): Spring fertilization can vary by microclimates. One of our writers lived in central Washington for years and cited that March to early May was usually go-time.
No matter where you live, resist the urge to cover your lawn with fertilizer just because it’s a nice spring day. Wait until the grass is actively growing. You should see even color and some growth. And, when in doubt, remember Reiter's question: “Have I mowed yet?”
Let Signs, Not Dates Guide Your Fertilizing Schedule
Rather than looking at the calendar, focus on your lawn’s behavior. Growth is your cue. If you see new shoots, thicker blades, and your mower has made a pass or two, you're safe.
What to look for:
- There are signs of grass growth—it's not patchy or dormant
- You’ve needed to mow at least once
- Soil temperatures are consistently above 55°F (you can use a cheap soil thermometer)
- Deep frosts are no longer a major concern (again, no chance of frozen soil or winter dormancy)
- Weeds are starting to sprout. This signals that your lawn will soon compete for essential nutrients.
Fertilizing at the right moment supports strong roots, fights broadleaf weeds naturally, and boosts healthy growth. Fertilizing too early feeds winter weeds, not grass. Fertilizing too late misses your lawn’s rapid growth spurt.
Should I use a slow-release or nitrogen-rich fertilizer in the spring?
For spring, a slow-release fertilizer is usually the best choice. It feeds your lawn steadily as it wakes up and starts growing. Heavy nitrogen fertilizers are sometimes used in summer or fall, depending on your grass type and region; however, high nitrogen levels in early spring can lead to fast top growth and weak root development. Always check the product label, and match the fertilizer to your lawn’s season and needs. And, when in doubt, ask the folks at your garden center to help you pinpoint the best choice for the current weather conditions.
Can I fertilize before my first mow if I want an early green lawn?
It’s tempting, but not a good idea. Neither granular nor liquid fertilizer will help much if your grass roots aren’t ready to absorb it. You’ll waste time and a dose of fertilizer, and possibly encourage weed growth. Wait until you see real signs of active growth and you’ve mowed at least once.
Is it okay to fertilize right after mowing?
Yep, it's actually a great time for balanced fertilizer. Mowing shows your grass is actively growing, which means it’s hungry. Just be sure the soil isn’t too dry, and water your lawn lightly after fertilizing if light rain isn’t expected soon. (With that said, if heavy rain is in the forecast, hold off until the storm passes and avoid accidental fertilizer run-off.)
