September Lawn Care

Lawn Care in September (A Guide for 2023)

Photo of author

Written By: Mark Marino

a Massachusetts Core Applicator License holder and owner/operator of Lawn Phix,

Updated on


No AI pledge. Authored and reviewed by Mark, not robots. Learn more.

If you buy something from one of our affiliate links, we may earn a small commission at no extra cost to you. I've used these products and provided an honest opinion on every product I review. This helps support our site and its free content, lawn care guides, and calendars. Learn more.

For my Northeast and cool-season lawn care gurus, welcome to my favorite time of the year – early fall lawn care!

The summer heat is pretty much behind us and cooler weather is ahead. This makes for the perfect conditions to repair your existing grass, throw down more grass seeds to build a thicker turf, or renovate and begin a whole new lawn.

As part of my month-by-month lawn care calendar, here’s the lawn care tips overview for September 2022.

September Lawn Care Tips

Core Aeration & Grass Seed

Late August and early September are prime times for core aeration and overseeding your lawn. Daytime temperatures are cooler and soil temperatures are still warm which is the perfect environment to establish a new lawn.

We have a detailed article on aeration and overseeding here, but here are some quick takeaways for your fall lawn.

Mow your grass short and dethatch. This will allow for better seed to soil contact and gives your new grass a chance to grow a little more evenly with the existing grass.

Core aerate your whole lawn with a double pass (up/down, and left/right). This will relieve soil compaction in your lawn, and allow oxygen, fertilizer, nutrients, and water to infiltrate deeper into the soil.

Fill in the bare spots of your lawn with grass seed and lightly rake into the soil surface to get the best seed to soil contact. Choose perennial ryegrass, turf-type tall fescue, or Kentucky bluegrass, or a blend of all three (like Jonathan Green Black Beauty Ultra), and grab a bag of one of the best starter fertilizers and lime.

Water frequently. Keep the grass seed moist for quicker germination. Once established, continue to spoon-feeding your new grass and lawn with nitrogen fertilizer

September is also a great time to apply top dressing to incorporate more organic matter into your lawns and soil. The next best time to do this is in the spring when the grass is actively growing.

Early Fall Maintenance

Out of all the months of the growing season, cool-season grass grows exceptionally well in the fall and September. The chance of fungal diseases in the lawn is much lower now as the temperatures will continue to cool outside of the fungus danger zone.

Continue to feed your lawn in the fall with a nitrogen fertilizer. Mow frequently and mulch your clippings. Also, begin to slowly lower your mowing height.

The days are shorter and the sun is not as extreme, so the need for taller grass blades is now behind us. Frequent mowing and spoon-feeding lawns will promote tillering and deeper root growth. Establishing a healthy lawn and root zone is vital leading into the winter – use a granular or liquid form of fertilizer.

Weed control for poa annua (annual bluegrass) – use a pre-emergent if you have not done so already. Note: you cannot use pre-emergent weed control (other than Tenacity herbicide) if you overseeded. This will target weed seeds but also prevent germination in your new grass seed.

If you overseed, skip the pre-emergent until next spring.

Technically, you can spray broadleaf weeds with a post-emergent weed killer, but keep in mind that these weed killers can affect your seeding window and harm your new grass. Only use one spot treatment and do not broadcast over the entire lawn surface. I suggest targeting these weeds with a broad spectrum weed killer next spring and focus on building your grass this time of the growing season.

Should I fertilize my lawn in September?

Yes. September weather is the best climate for cool-season lawns. This is the time of year that you can repair your grass from the summer months, push new growth, develop healthy roots, and even renovate your lawn.

Is it too late to fertilize my lawn in September?

No, September is perfect to feed and fertilize your lawn. Choose a higher nitrogen fertilizer – or even a starter fertilizer – to refeed your grass and

Was the information on this page helpful?

Thanks for your feedback!
Author's Note: this piece has been updated for accuracy since its first publication on
Photo of author
Author: Mark Marino
My name is Mark Marino, and I am the founder, owner, and operator of Lawn Phix. With a passion for lawn care and turf nutrition for over a decade, I've dedicated countless hours to correcting soil and perfecting lawns. Today, my expertise, backed by formal courses at UMass Extension Pesticide Education, allows me to offer top-tier lawn care services and advice. I am a fully licensed and insured lawn care applicator in Massachusetts, specializing in comprehensive turf nutrition, weed control, and lawn pest control. My license number is AL-0053865. Contact me at [email protected] or +1 (508) 500-8402.

2 thoughts on “Lawn Care in September (A Guide for 2023)”

  1. Hi! I’m wondering if it’s advisable to use a electric dethatcher in the spring before a spring overseeding here in Massachusetts? I overseeded this fall, but perhaps too late in my backyard, which is in worse shape and receives less light than my front yard. (Newly purchased house, existing lawn). Just want to make sure after winter I get good soil contact with seed without tearing up too much of the thin, but existing, lawn.

    • Hi Matt – I don’t think I’d recommend dethatching this upcoming spring, especially after seeding this fall. Dethatch and core aeration prior to overseeding is best for late August – early September here in Massachusetts. Depending on the current state of your lawn, and grass type, you’ll need to adjust the amount of grass seed (eg: 7-10 lbs of a blend like Jonathan Green Black Beauty Ultra on a poor/thin lawn). If you didn’t have good results this fall, you might need more seed.

      I’d recommend a soil test in March and feeding your lawn in April to push as much growth as possible. I really do not like seeding in the spring unless you have to (i.e. a new lawn).

      Hope this helps.


Leave a Comment