What’s the Best Time to Overseed a Lawn in the Northeast?

If you’re looking for a way to improve the thickness and quality of your lawn without having to kill it and start from scratch, then overseeding is the technique for you. Overseeding your lawn can also help to inhibit weed growth. When you overseed, you will notice a wonderful improvement in your lawn’s color and density. In this article, I will go over when the best time to overseed a lawn in Northeast states is.

Let’s start with the basics.

What is Overseeding?

Overseeding is the process of spreading and planting new grass seed on an established lawn. It’s a process that will help improve the density, color, and general appearance of your lawn.

Overseeding is also beneficial for general lawn health. It’s one of the easiest ways to thicken and re-invigorate your lawn.

A pro-tip is to overseed annually as a preventative measure to ward off thinning and keep weeds at bay. If you wait for a problem to develop in your yard before you act you’re just making more work for yourself.

Like most areas of life – it’s easier to prevent a problem than it is to fix a problem.

And if you’ve had (or currently have) an issue with lawn weeds, then overseeding can help.

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What’s the Best Time to Overseed a Lawn in the Northeast?

The best time to overseed a lawn in Northeast states is in the fall, though you can have success overseeding your New England lawn in the spring as well. These two times of year are when cool season grasses used in northeastern US lawns grow best.

My advice is to plan your overseeding project for the fall if possible. You’ll have less competition from annual weeds like crabgrass if you overseed in the fall, meaning your seedlings won’t have to fight for light, nutrients and water – they can just grow!

Why Fall?

As the summers are hot and the growing season short in New England, early fall is ideal for overseeding your yard.

The soil is still warm from summer (which helps with germination), annual weeds are dying back, and the cooler weather and increased rainfall allow your new grass to get established well before winter arrives.

Spring can work, but it’s trickier to time it right.

The Trouble with Spring

In the spring you have to make sure that you wait until the soil warms to the right temperature for grass seed germination, and you have to try to find a pre-emergent that blocks crabgrass (but not your seed).

Then your seedlings have to survive the gauntlet of heat, drought, and weed pressure.

It’s tough, but you can have success if you stay on top of things and are prepared to do some extra watering and weed control.

Never in Summer

Will your grass seed germinate in summer? Of course. There’s plenty of sun, and warm soil. But keeping your seedlings alive will be challenging and take a lot of time, energy, and resources.

You’re risking your expensive seed if you overseed in summer, and my advice is to wait a few months and do it right in the fall.

More Thoughts About Overseeding at the Right Time in New England

Overseeding will have the greatest chances of success with the ideal combination of

• warm soil,
• low weed pressure, and
• cool air.

Cool air helps to stimulate grass growth, and the warm soil speeds up germination.

Another advantage of overseeding in the fall is the fact that between mid-August and mid-September in the northeastern states, many weeds are no longer germinating.

This means that all of your water and fertilizer isn’t being wasted on the plants trying to crowd out and kill your new grass.

One caveat – make sure to do your fall overseeding early enough that leaves are not yet falling in large quantities.

Fallen leaves can smother grass seedlings, so you’ll want to remove them quickly (here are some tools that can help).

If you choose to overseed in the spring instead (maybe you bought your home in the late fall and winter and are itching to get out there and do some work on your yard), then don’t make it so late in the spring that the heat of the summer could negatively affect your fledgling shoots.

However, it should be late enough that the soil temperature is at least 50°F before you do your overseeding – if the soil is too cold your seed won’t germinate at all.

A good rule of thumb is to spread your grass seed when the lilacs start to bloom.

When you overseed in the fall, the seeds will have time to get properly established before the rigors of winter arrive. This is an especially vital benefit if you end up having a hot spring with very little rainfall.

You can spread pre-emergent in the spring (here are my favorites), fertilize your rejuvenated lawn (here are the best spring fertilizers), and enjoy the fruits of your labor.

Why is Overseeding So Helpful?

Overseeding is primarily a method used with cool-season grasses in northern areas of the United States, though some people overseed their warm-season grass lawns with Ryegrass when their lawns go dormant (to maintain a green yard).

Cool-season grasses are (for the most part) bunching grasses. Examples of bunching grasses are fine fescue, tall fescue, as well as perennial and annual ryegrass. Bluegrass is sometimes considered a bunching grass as well, though most varieties spread slowly via rhizomes.

With bunching grasses, blades of grass emerge when the seeds germinate. At the center of the plant is the grass crown. This has roots that grow down from the crown. There are blades that grow upwards. As new tillers (or grass blades) develop, the grass plant expands. The tillers grow in addition to the original crown.

Eventually, there may be hundreds of tillers. Each tiller has its own crown and roots, as well as blades. Each blade of grass lives only a very short time, just six weeks. If new tillers aren’t produced, then your lawn will become thin and sparse.

These characteristics and needs of bunching grasses make overseeding so effective.

It continually breathes new life into your lawn, which keeps it looking young and vibrant, filling in thin and bare patches where weeds may take root if you don’t overseed.

Overseeding Tips

There are certain steps that you need to take before overseeding your lawn.

First, mow your lawn to a shorter height and get rid of all the clippings. This is important, as it will ensure that the seed you spread makes proper contact with the soil and is able to get the water and sunlight it needs.

Whatever method you choose to overseed your lawn, make sure that the seed will be evenly distributed.

Overseeding a Small Yard

You may not need to buy a fertilizer spreader if you have a smaller lawn. When doing overseeding by hand, first divide the seed up into two even halves.

Broadcast one half of the seeds to the entire area. Do this while walking in one direction. Walk in the opposite direction while spreading the rest of the seed. This should be done from a right angle to the direction you walked in for the first half (i.e. north-to-south, then east-to-west).

By choosing two directions when you broadcast the seed, you will enjoy the best chance of proper coverage.

Overseeding a Mid-Size Lawn

If you are overseeding a slightly larger area, then you can use a small hand-held rotary spreader.

You can usually find one of these for a very reasonable price. I own this one from Scotts and it cost me around $20.

Small hand-held rotary spreaders generally offer greater precision than trying to spread the seed by hand.

Overseeding a Large Lawn

If you have a larger area, then you should use a drop or rotary spreader.

These larger spreaders are probably the same kind you used in the past to apply lawn fertilizer. Many homeowners prefer using broadcast spreaders for overseeding (and I’m one of them).

The type of lawn grass seed that you select should depend on the kind of grass you already have on your lawn. Look for products made specifically for overseeding the kind of lawn you have.

If you like, you can use a seed that is pre-mixed with a fertilizer and a soil improver like Scotts Rapid Grass (here that is on Amazon, and at The Home Depot).

If you’re just using seed, I recommend using a good starter fertilizer (here’s a list of my favorites) at the same time you spread your seed, and top-dressing with about a quarter of an inch of screened compost (any more and your seed may not germinate).

Aerate Before Overseeding

My recommendation for amazing results is to aerate just before you do your overseeding.

Aerating is a process through which you put holes in the ground that allow sun, water, and nutrients to easily reach the roots of your lawn grass. I have an in-depth lawn aeration guide you can read here.

I find that aerating just before overseeding is a very effective way to get great seed to soil contact – many of your seeds will actually fall into the holes and help to quickly thicken your yard’s grass.

The most effective type of aeration is core aeration (sometimes called plug aeration). Core aeration involves removing a plug of grass and soil from the lawn. Each plug pulled should be about a half an inch wide and three inches long.

Spike aeration differs from plug aeration slightly, but it can also be effective (you just have to do it more frequently).

You can rent an aerator from Home Depot to do the job.

Do Your Dethatching

Some lawns will benefit from dethatching before you aerate and overseed.

Thatch is the layer of dead plant material that builds up at the base of your grass. Over time, if this layer becomes too thick it can smother your lawn by preventing water, air, and nutrients from reaching the soil.

When overseeding, you need your grass seed to come into contact with your soil to germinate, which is why dethatching, then aerating, and then overseeding and lightly top-dressing your yard may be your best sequence.

Dethatching is the process by which the layer of thatch of the area is removed. A thatch rake is can be used for the job, but if you have a larger yard you’ll want to rent or buy a dethatcher to do the trick.

Dethatching with a thatch rake will also help you quickly locate grassy weeds, such as crabgrass and clear the soil there for some extra seed. The stems and blades of these plants are generally longer than those of grass. After you are done dethatching, put the thatch in your compost pile.

Keeping a compost pile for grass clippings and other yard waste is something I love and recommend if you have the space for it. It’s a great way to accumulate excellent fertilizer for your lawn and garden.

Wait, This Project is Getting Out of Control…

When you start to add aeration, dethatching, top-dressing, and seeding your lawn together, it sounds like a lot of work (and it is).

But this is a lawn renovation you can complete by yourself in a single 3-day weekend and you’ll be amazed by the results.

It’s a project weekend I do every other fall on my lawn here in New England, and I have a complete schedule for this sort of overseeding project weekend which you can check out at the very bottom of this page if you’d like to learn more.

And if you’re interested in learning my exact process for caring for my lawn each season, grab my free cheat-sheet right here.

I hope your overseeding project goes well this year!