When & Why You Should Overseed Your Lawn

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Are bare spots and thinning grass blades plaguing your lawn? Do you fertilize your lawn and seed the soil every spring, but your turf just won’t grow as lush and green as you hope it will? Heartland Turf & Landscape would like to help you understand why overseeding may have failed in the past and how it can help save your lawn this year!

What Is Overseeding?

Overseeding is an easy method of planting grass seed that avoids disturbing the soil in your yard. As opposed to new lawn seeding, which is planting an entirely new lawn from scratch, overseeding simply requires landscapers to plant new grass seeds over an existing lawn. Overseeding does not require machinery or chemicals, and it can be accomplished as easily as reaching into a bag of grass seed and tossing seed over the struggling lawn.

When To Overseed Your Lawn


Overseeding should take place in fall, typically between late August and early October. Let us explain why!

In the Kansas City area, we recommend that lawns be seeded with a cool-season grass that is best acclimated to our temperate climate. The most common grasses used in our area are Kentucky bluegrass and tall fescue, both of which are designed to thrive in cooler temperatures. If these seeds are planted outside of the appropriate season, they will struggle to germinate and grow in the heat of summer, and you will have to lay new seed in the fall anyway.

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Fall is also the time of year when aeration should take place. Aerating your lawn allows for improved nutritional intake and healthier soil, and performing aeration in fall allows compacted lawns to decompress after the stress of summer heat and traffic. Aeration creates the perfect environment for seeds to germinate, which is why we always recommend that overseeding be performed alongside aeration in fall.

Aside from the season in which overseeding should take place, there are a number of other factors that should help you determine when to overseed. For example, a particular year may experience colder temperatures arriving earlier than usual. In these cases, a consistent ground temperature around 50 degrees is a good indicator that it is time for overseeding.

water puddling up on a lawn

Other important factors concern the condition of your lawn. If you notice any of the following issues on your lawn, overseeding should be performed in fall or possibly even sooner if the damage is severe:

  • Thin Grass
  • Bare Patches
  • Invasive Weeds
  • Brittle Grass Blades
  • Undesirable Grass Types
  • Spreading Fungal Infections
  • Pest Damage
  • Poor Drainage

Can You Overseed In Spring?

Just as cool-season seeds need cooler temperatures to germinate, warm-season seeds perform best when they are planted in the warmer weather of late spring or early summer. However, we do not recommend using warm-season grass seed for lawns in the Kansas climate zone, which is why Heartland Turf & Landscape only overseeds in fall.

Spring should be the time of year when pre-emergent is applied to your lawn. Pre-emergent is a type of herbicide that produces a protective barrier across the soil surface to prevent weeds from emerging. Unfortunately, the best pre-emergents are of the non-selective variety, meaning that they will prevent the growth of any vegetation, not just undesirable weeds and grasses.

The application of pre-emergent in spring is crucial to the health of your lawn, as it is the best method of choking out weeds before they can disrupt new grass growth. Even if pre-emergent is not applied, cool-season grass seeded in spring will develop shallow roots because conditions are not ideal. For both of these reasons, we can not recommend overseeding in spring.

Why You Should Overseed Your Lawn

Lawn Health

The benefits of overseeding do not take long to discover. If seeded in the proper season, with the proper aftercare, your lawn should start improving in just a couple weeks. Below are just a few of the many benefits you can provide to your grass by overseeding.

Thick Lawn

Overseeding adds more grass to lawns that may already have a decent amount of coverage. Each single little chute of grass that comes from a single seed will mature into 30 to 40 individual grass blades. Before you know it, those bare and thin spots will fill in, and your lawn could be more lush than you ever would have imagined.

Green Grass

Fertilizing is a necessary step to take in creating a greener lawn, but overseeding can also play a pivotal role in this task. Fertilizers need existing root systems and growing grass in order to take effect. If your lawn has dead patches, overseeding can help by producing more healthy roots that can absorb nutrients and green-up that grass.

Erosion Protection

More grass means stable soil and reduced water runoff. As the seeds begin to germinate and seedlings turn to mature grass, there will be more material present to absorb water and prevent erosion. Your lawn will also become healthier as it absorbs more water, which helps your lawn avoid standing water and puddles.

Weed Control

Weeds compete for the same nutrients that your lawn needs. If there is not enough healthy turfgrass present in your lawn, weeds will easily be able to overtake the weaker roots and plants of your lawn. Overseeding gives your lawn the chance to develop healthy grass roots that can then overpower harmful weeds.

Disease Prevention

Fungal lawn diseases spread quickly across struggling lawns. If overseeding is performed correctly, invasive fungi will have difficulties spreading across the newer, healthier grass. As the spread of lawn disease is slowed or ceased, your grass will have the opportunity to repair itself and better defend itself against diseases.  

Pest Control

Lawn pests, such as mosquitoes, wasps, and ants, are notorious for hanging out in and around damaged lawns. Standing water and thinning grass create an ideal environment for pests, but overseeding will help prevent such issues. Having a thick lawn that drains properly is always the best way to prevent lawn pests.

Changed Grass

If you have discovered undesirable grass types like Bermuda or St. Augustine in your cool-season lawn, overseeding can help correct the issue. Glyphosate can be used to kill the existing grass so you can lay down new seed without having to completely tear up and turn over the existing soil.

No Chemicals

One of the most appreciated things about overseeding is how simple and eco-friendly it is. Though applying fertilizers can certainly help, overseeding can be effective simply by seeding thoroughly and watering deeply. With consistent aftercare, your lawn will be lush, green, and chemical free.