What Happens If You Let Grass Grow Too Long?


A consistent lawn care routine that involves watering, fertilizing, and mowing is essential to maintaining optimal lawn health. Moreover, keeping the grass at an appropriate height not only makes your landscape look better but also encourages stronger root growth.

But have you ever wondered what happens to grass if you don’t cut it? 

It’s easy to get lazy and let your grass grow too long. But in addition to its unsightly appearance, an overgrown lawn can create a conducive environment for pests and weeds. These issues can significantly affect your lawn’s overall health, requiring a more extensive maintenance and rehabilitation strategy.

Here’s What Happens When You Don’t Cut Your Grass

After a few months without mowing, your grass can spiral out of control. As it reaches a certain height, it loses its ability to support its weight and starts to bend over, causing the grass to clump together and your lawn to look uneven.

Overgrown lawns may also reveal bare patches and weeds and start to attract insects and pests. While occasional lapses in lawn mowing will not necessarily lead to this extent, it's common in newly purchased properties that have been left unattended for an extended period by their previous owners.

The Problems with Overgrown Grass

While a well-manicured lawn is universally appreciated, not everyone is willing to put in the effort. However, choosing to skip lawn mowing introduces a host of other challenges beyond aesthetic and pest issues.

Poor Grass Health

Regular mowing encourages grass to develop broader and deeper roots, contributing to a healthy and resilient lawn. But when your grass goes too long without a trim, it becomes weak and may grow unevenly. The grass blades may also turn yellow or brown.

An overgrown lawn risks suffocating itself, preventing sunlight and essential nutrients from reaching the roots. It also absorbs more nutrients than your soil may provide, further weakening the grass and may also become more susceptible to pests, fungi, diseases, and weeds.

Difficulty in Mowing

Letting your grass grow more than the recommended cutting height makes mowing more difficult. It will potentially require adjustments to your mower blade. But even with that, it's essential to follow the one-third rule, trimming no more than one-third of the grass height at a time. When you let the grass grow too long and then suddenly cut it, you risk sending the grass into shock. It can weaken your lawn by slowing down root growth and making it more susceptible to damage.

Additionally, mowing long grass can damage your lawn mower, as the excessive height may strain its sharp blade. This added stress can lead to increased wear and tear on the equipment.

Health Risks

Overgrown grass creates an unsightly look. But, not only you will be dealing with this aesthetic issue, but also with the damage it can cause to your yard.

An overgrown lawn with tall grass creates a conducive environment for pests, which can be harmful to anyone with access to the lawn. The dense and tangled vegetation also creates favorable conditions for the development of moss, thatch, as well as fungal infections, further compromising your lawn's health.


How to Mow Overgrown Grass

There's hardly any point in keeping tall grass. But cutting it addresses the many issues associated with it by deterring pests that may think of making your lawn their home, preventing weed overgrowth, and encouraging deeper and stronger roots.


Regain control over an overgrown lawn by addressing its excessive height first. If the grass is too high to use a mower, use a line trimmer or brush cutter, which are equally versatile tools for trimming grass. Reduce the height gradually, spacing out the initial trim from the subsequent cuts by 2-4 days, until the lawn is at a manageable height for mowing. This gradual approach minimizes the shock to the grass, allowing for a smoother transition to a regular mower.


Wait at least a week after the initial trimming before mowing the lawn. While it's tempting to cut the grass down to your desired mowing height in one go, make sure to adhere to the one-third rule, removing only one-third of the grass height each time you mow.

Limit your mowing sessions to once per week until you reach your usual mower height, and then maintain a regular mowing routine as necessary. This will be much less stressful for the grass, giving it time to recover—and the less stress, the healthier and denser your lawn will be in the long term.

Dethatch and Aerate

After trimming your grass down to its recommended mowing height, it's time to dethatch your lawn to remove the thick of debris that has accumulated over time. It's also the perfect opportunity to aerate your soil by perforating the surface with small holes.

Although these steps are critical in reclaiming an overgrown lawn, it's advisable to wait until after the grass is under control. Overgrown lawns that have been neglected for a long time often accumulate thatch and suffer from soil compaction, both of which can stunt grass growth and create a conducive environment for fungi and weed to grow.

By dethatching and aerating, you improve drainage and allow air, water, and nutrients to reach your grass and soil more effectively. Overall, these contribute to the overall health of your lawn.

Repair Damaged Lawn

With the lawn surface cleaned up, any damage—such as sparse areas or bare spots in your lawn—may have become more apparent.

Consider planting grass plugs instead of seed to fill in these areas. These small, pre-grown sections of grass with established root systems provides a more immediate and uniform coverage. Unlike seeds, grass plugs establish faster, guaranteeing a higher chance of success and reducing the risk of weed growth.

Stick to a Regular Lawn Care Routine

Remember to keep the lawn consistently moist for 10-14 days after planting. This will aid the plugs in adapting faster to their new environment. Then, water less often and more deeply to encourage deeper root growth.

How and when you will fertilize your soil will vary slightly depending on the grass type. However, we recommend using a starter fertilizer to kickstart the growth of your newly planted grass. NutriPod is a slow-release grass plug nutrition with a higher nitrogen content to specifically promote leaf growth. Its slow-acting nature guarantees the gradual and steady release of nutrients to support stronger root growth and overall healthy grass development.


Final Thoughts

Sure, you can get away with delaying your lawn mowing for a day or two. But leaving grass to grow excessively for extended periods can have significant effects on your lawn—an increased risk of pests, diseases, and weed growth, to name a few.

Taking the necessary steps to address overgrowth, including proper trimming, dethatching, and aeration, is essential for maintaining a vibrant and resilient lawn for the long term.

Got more lawn care tips to address overgrowth? Let us know by leaving a comment.


Jamie Tedder

Jamie surrently serve as Vice President on the board for Turfgrass Producers of Florida. He currently oversees the production of all grasses throughout all farms in Florida at Bethel Farms. He is actively working with top grass breeders, researchers, producers and end users from public and private institutions around the country to stay up to date on current industry developments. Being a University of Florida graduate, he has applied that knowledge to over 22 years of experience growing spectacular grass!

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