The depth of your grass roots plays a vital role in the overall health of your lawn.
Deep roots keep grass stable and absorb more water and nutrients from the soil.
When your grass roots are shallow, your lawn is prone to bare spots and soil erosion.
So how deep do grass roots usually grow?
On average, grass roots will reach a depth between 6″ inches and 3′ feet into the soil. The root depth of your grass depends on several factors, such as grass type, soil health, and how often your lawn receives water.
The more established your lawn is, the longer the grass roots will be.
Keep reading to learn more about how deep grass roots will grow and why some grass types have longer roots than others.
Table of Contents
How Deep Are Grass Roots?
Grass starts establishing a root system soon after the seeds have germinated.
As long as the soil is healthy and not compacted, the grass roots will grow at least 6″ inches into the ground.
It is not unheard of for a well-established healthy lawn to have grass roots deeper than 3′ feet into the soil.
Fertilizing your lawn early in the growing season as the new seedlings emerge gives the new grass the boost it needs to form a strong root system.
Without a deep root system, your grass will become uprooted easily by everyday activities such as walking or mowing.
Your grass will also be more prone to damage from wind and rain if it does not have healthy roots.
When your grass becomes uprooted, your lawn will have areas of patchy growth or unsightly bare spots.
Fixing this damage is often time-consuming and expensive, so it is best to encourage healthy root growth from the beginning.
Does Grass Have Shallow Roots?
Certain grass types naturally have shallow roots, such as Kentucky bluegrass and bentgrass. The most common causes of shallow roots in any type of grass include compacted soil and improper watering and mowing techniques.
Compacted soil is the biggest reason for grass roots to be shallow.
The soil on your lawn naturally becomes compacted over time by heavy foot traffic or lawn care equipment.
Compacted soil not only prevents roots from growing deeply, but it also has poor drainage, which causes standing water to pool on your lawn.
Many homeowners use sand to solve the problem of drainage issues.
However, if there is a high clay content in your soil, adding sand to the mixture may worsen.
Sand and clay together will harden like concrete when wet, which is not a desirable outcome.
A better way to deal with soil drainage and compaction is to aerate your lawn.
Aerating the soil adds holes to the ground to allow water and essential nutrients to reach plant roots.
Aeration also loosens the soil slightly to allow the grass roots to grow deeper.
Grass will also develop shallow roots if it does not receive adequate water or is not properly mowed.
New grass sprouts need to be watered several times per week to encourage healthy growth.
Your grass will have a weak root system without enough water, and grass growth will be thin.
Cutting the grass too short when you mow will stunt its growth and cause shallow roots.
Always follow the one-third rule when you mow by only cutting one-third of the length of the grass blade at one time.
No matter how well your lawn is maintained, some grass types like Kentucky bluegrass or bentgrass will always have shallow roots.
These grass types will always have a weaker root system, and they are usually overseeded with other grasses to counteract this issue.
What Depth Do Grass Roots Grow?
Most grass roots are concentrated in the top 6-8″ inches of soil. Strong root systems can grow up to 3′ feet into the ground if conditions are just right. If you have a rock layer beneath your soil, your grass roots may grow horizontally once they reach this layer.
Healthy grass will have a long, white root system growing deep into the ground.
Watering is essential to promote root growth, but it is beneficial to allow your grass roots to dry out a bit in between watering sessions.
When grass roots become dry, they push down into the soil in search of water.
Watering deeply but infrequently will encourage the roots to grow even deeper into the soil as they search for water.
When a lawn is well-maintained for many years, its grass roots may reach a depth of more than 3′ feet.
Does Grass Grow in 2″ Inches of Soil?
Neither grass seeds nor established grass will thrive in only 2″ inches of soil. The ideal soil depth for grass to root properly is between 6-8″ inches. If grass seeds are planted under 2″ inches of soil, many seeds will not germinate because they will remain dormant.
Ornamental grasses have rhizomes which make the roots spread laterally, so they will do well in shallow soil.
However, covering an entire lawn with ornamental grasses is not ideal as these grasses are only meant to be featured as accent plants and not lawn cover.
Even if your grass does grow in shallow soil, its growth will be short-lived.
Without enough soil for the roots to grow deeply, the grass will easily be uprooted by weather or foot traffic.
It will likely be thin and sparse if the grass survives because the short roots will not absorb enough nutrients to keep the plant healthy.
Your lawn will appear patchy, and you will likely have several bare spots where the grass has become uprooted.
Grass with shallow roots will also be more susceptible to damage from extreme hot and cold temperatures and fungus and disease.
What Grass Has the Deepest Roots?
Bermuda grass has the deepest root system of warm-season grasses, with roots growing as deep as 8′ feet. Tall fescue has the longest roots growing more than 2-3′ feet deep into the ground for cool-season grasses.
In general, longer grass types naturally tend to have deeper roots.
Warm-season grasses, like Bermuda grass, need longer roots to help them survive in extreme heat and drought conditions.
While most of the root system of Bermuda grass is in the top 12″ inches of soil, the roots can grow more than 8′ feet into the ground in proper soil conditions.
Bermuda grass does not tolerate shady areas very well, but it will spread and thrive in areas with hot summers and mild winters.
Bermuda grass is an excellent choice for the Southeastern United States and parts of California.
Cool-season turf grasses are usually taller than most warm-season grasses.
Tall fescue has the strongest root system out of all cool-season grasses, with roots growing as much as 3′ feet deep.
This deep root system makes tall fescue the most drought-tolerant cool-season grass as well.
Tall fescue also thrives in transitional climates, which receive both warm and cool temperatures during the year.
Tall fescue will grow well in the shade, but it is not tolerant of heavy traffic.
Since fescue does not spread easily, it will be challenging to fill in any bare patches which may occur.
Why Are Deep Roots Important?
Deep roots are important to a lawn because they provide oxygen, nutrients, and water to the grass blades. Deeper roots mean they can absorb and retain more of these vital resources for the plant.
Water usually soaks into the upper layer of soil and then drains into the subsoil underneath.
This water deposits essential minerals and nutrients into the soil layers as it drains down.
If your grass has shallow roots, it will not receive any nutrients that drain past the first few inches of soil.
Every time your lawn is watered, these nutrients will be pushed further down into the soil where the roots do not reach.
The top layers of soil also do not retain much moisture due to evaporation.
If your grass has shallow roots, it will only receive as much moisture as these upper layers of soil will provide.
As a result, your lawn will become stressed, and your grass will become discolored or die due to the lack of nutrients and moisture.
In addition to the ability to absorb more nutrients and water, deep roots prevent your grass from being pulled out of the ground easily.
This added strength protects your grass against harsh winds and excessive foot traffic.
Deep roots also protect your grass against drought due to the extra moisture retention.
The ability to absorb more nutrients will also help your deeply-rooted grass fare better during its winter dormancy.
How Do You Encourage Deep Root Systems?
The best way to encourage your grass to form a deep root system is through proper mowing and irrigation techniques.
This section will explore these two techniques and learn how they encourage deeper root growth in your grass.
Every time you mow your lawn, the grass roots will grow deeper into the soil to overcome the stress of the blades being cut.
The roots may also spread laterally to allow more blades of grass to come up through the soil’s surface.
Regularly mowing your lawn encourages your grass to focus its energy on root growth instead of blade growth.
Always follow the one-third rule when mowing your lawn, and never cut more than one-third of the length of your grass blades.
If you cut your grass too short, it will have a difficult time recovering, and it may suffer from permanent damage.
It is always best to cut your grass to the proper height according to its type.
Check out our article answering the questions around frequent mowing and thick grass.
The following table shows the recommended mowing heights for some common types of grasses.
|Recommended Mowing Height
Watering your lawn at the correct frequency and depth is important for encouraging grass to form a deep root system.
Many homeowners rely on a sprinkler system, and they usually set it to operate daily.
The problem with daily irrigation from a sprinkler system is the soil is only being watered in the upper surface layers.
This method causes the roots to stay closer to the soil’s surface to absorb the water.
Instead, it is best to allow your lawn to dry out a bit in between watering sessions.
The roots will grow deeper into the ground to find moisture by letting the upper soil layers become dry.
Watering your lawn for an extended period and allowing the deeper soil layers to become soaked will cause the roots to grow even deeper.
1-2″ inches of water per watering session will be enough to soak the soil without causing the ground to become too soggy or water-logged.
To keep your lawn lush and healthy, the following irrigation schedule is recommended:
- Once per week in the spring and late fall.
- Twice per week during early summer and early fall.
- Three times per week in mid to late summer.
Your grass will grow a healthy, robust root system by following a regular watering routine and giving your lawn the right amount of moisture.
Have weak water pressure? Check out our tips for increasing water pressure in your sprinkler system and hoses.
What Are the Symptoms of Unhealthy Root Systems?
If your grass is wilted, discolored, infested with weeds, or there are dead patches, your lawn likely has an unhealthy root system. Most lawn problems are caused by poor watering techniques, stress, diseases, pests, and improper fertilization.
If you are able to see your footprints after walking through your lawn, your grass is wilted and likely needs to be watered.
When your grass is wilted for several days at a time, the roots will die back from being too dry.
If your lawn is also soggy in addition to being wilted, this means you are overwatering your lawn.
Overwatering is a more serious problem for the root system as the grass roots will start to rot if there is too much moisture over a long period.
You will need to let your lawn dry out significantly before resuming a normal watering schedule again.
If your lawn is too wet because of heavy rainfall, you need to consider aerating your lawn and implementing a better drainage system, such as a French drain.
Discoloration or Scorching
If you have recently fertilized your lawn and your grass has turned yellow or brown, you are likely dealing with fertilizer burn.
Too much nitrogen will scorch your grass blades and may lead to root death.
The only way to remedy this situation is to thoroughly water your lawn and dilute the excess fertilizer.
Be careful doing this around nearby lakes and streams because the fertilizer runoff is toxic to aquatic wildlife and may cause algae blooms on standing water.
A safer alternative to fertilizer is compost, which will work over time to produce a healthier lawn.
Weeds thrive in poor soil conditions, so your grass roots are suffering if you have a weed infestation in your lawn.
Weeds take away essential nutrients from your grass, and they may be the result of soil compaction or a nutrient deficiency.
Unhealthy soil equals an unhealthy grass root system, and it is recommended to have your soil tested to learn what it may be lacking.
Herbicides are a temporary solution and may cause harm to your healthy grass, so it is better to establish a regular mowing schedule to prevent the weeds from spreading in the first place.
You may need to manually remove existing weeds as well.
Dead or Brown Patches
If you notice dead or brown patches of grass on your lawn, you may have a pest problem.
Grubs are the most common cause of dead grass areas, and these pests will destroy your lawn’s root system.
If you suspect a grub infestation, you will need to dig up some of your grass for verification and then treat the area with a pesticide.
You may need to overseed your lawn to help it recover, especially if you have cool-season grass.
Commonly Asked Questions
Are there alternatives to turf grasses for lawns?
There are alternatives to having grass on your lawn, but it is best to check with your local city ordinances or HOA because some places do not allow food to be grown in your yard.
Using native plants to landscape instead of grass is also a great alternative, especially in areas with little rainfall.
What if water restrictions prevent me from watering my lawn in the summer?
If you live in an area prone to water restrictions during the hot summer months, you probably have warm-season grass in your yard.
Warm-season grass will go dormant when it does not receive enough water, but it will come back to life once a regular watering schedule is established once again.
You may also consider installing a rainwater collector near your drain spouts so you will still be able to water your lawn.
What is a root stimulator?
A root stimulator contains auxin hormone, which stimulates root development in young plants.
Root stimulators also protect the grass roots from stress and damage.