How Deep does Grass Roots Grow?

Establishing a beautiful, lush green turf takes a lot of work and patience. Seeding, watering, fertilizing, and weeding is part of the process and a great way of promoting healthy lawn growth.

However, all that work may be for nothing if your grass doesn’t have deep roots. Without deep roots your grass can easily get damaged and may not be able to reach the nutrients in the soil it needs to thrive.

Deep roots will help your lawn survive stressful conditions which are why creating a healthy, deep root system is an important part of lawn maintenance.

But how deep do grassroots grow? Lawn grasses planted in healthy soil will usually have a root depth of 6’’-2’ with a long, white, and dense root system. However, the root depth will greatly depend on the health of the underlying soil and your lawn care maintenance schedule.

How to achieve deep root growth in your lawn

The first thing that comes to mind when you look at your lawn is the healthy and green leaf blades, but you don’t often think about what goes on underneath the soil that makes the grass blades green, thick, and healthy.

The grass root system is very important to the overall health of your lawn.

There are many ways you can encourage deep and healthy root growth.

  • Mowing

Adjusting the cutting height of your mower can help to encourage deep root growth, but don’t cut more than 1/3 of the grass blades when mowing.

Mowing creates stress by removing growth which will cause the grass to respond by growing deeper roots so that it can sustain more leaf growth and the leaves grow taller.

Consistent mowing will help create dense, deep root systems.

Warm-season grasses tend to grow outward not upward so you need to use shorter mowing heights.

However, cool-season grasses grow upward which makes it a bit harder to establish a thick, dense lawn, but they grow taller which makes them look fuller.

  • Watering

Watering your lawn frequently doesn’t automatically mean you have a healthy lawn, it might even actually be hurting your lawn.

This is because watering frequently can create shallow roots growth, but the key is to water deeply less frequently.

Deep infrequent watering creates stress by allowing the roots to dry out so the grass grows down in search of available water.

However, it’s important that your lawn stays well-hydrated to sustain deep root growth since this allows moisture to penetrate deeper into the roots when you water your lawn.

To create and sustain deep root systems, you should water your lawn twice a week in spring, twice a week in early summer, thrice a week in mid to late summer, twice a week in early fall, and once a week in late fall.

Ensure the water is 1-1 ½ inches deep.

  • Soil condition

The condition of your soil plays an important role in the development of deep root growth. Heavy clay soil will retain water very well, but it will also compact easily reducing the air pockets that provide your grass with the oxygen needed to thrive.

Adding organic matter like compost will add important nutrients needed for root growth and help loosen the soil to create more room for more air pockets.

  • Use correct fertilizer

A slow-release fertilizer is the best for promoting grass root growth by releasing nutrients slowly that are distributed over a long period.

As opposed to using a fast release fertilizer that is less expensive but it releases all the nutrients at once and most of the nutrients aren’t used by the plants and don’t reach below the root zone.

Mineral fertilizers have a high salt content so you need to water your lawn to keep it from burning. If the conditions are conducive, about 80% can reach below the root zone which will be used to help develop deep grass root growth.

  • Check the soil pH

Different grass types require slightly different soil pH to grow best in and if your soil doesn’t have the required pH, you can easily adjust it.

First, take a soil sample to your local extension office to check the soil pH. You can add organic matter if the soil pH is slightly off, if not use limestone for acidic soils or sulfur for alkaline soils where needed.

  • In-ground irrigation system

An in-ground irrigation system can help promote deep root growth in your lawn.

By using weather sensor technology and programmable settings, you can eliminate the guesswork and hassle you’ll put into watering your lawn.

You can come up with a watering schedule that will take into account the amount of moisture your lawn has received from nature and the amount of water it needs to stimulate healthy deep roots.

How to develop deep roots in grass

Getting your grass to grow deep roots is mostly a matter of ensuring the soil underneath your grass has enough moisture.

  • Find out how deep the roots are for your grass by digging into the soil or using a soil probe to check the root depth. Grass that is properly established should have roots that are several inches deep.
  • Water your lawn weekly with 1-2 ½ inches of water or more if needed so it can penetrate the soil about an inch below the current root depth. Your grass won’t develop deeper roots if there’s no water beneath the current root growth.
  • Remove any excess thatch with a rake or dethatching blades if the water isn’t penetrating the soil as it should. Thatch which is dead organic matter from grass clippings and leaves if left to buildup can form a barrier over your soil that prevents enough water, air, and sunlight from penetrating the soil and this will starve your grass.
  • Use a core aerator to aerate your lawn which will help to reduce soil compaction and improve water penetration. The core aerator will break through the thatch and allow air into the compacted soil as it removes small soil plugs on your lawn.
  • Mow your lawn regularly and ensure your cutting blade height is about 2 1/2 – 3 inches tall so that the grass will provide some shade so that the soil stays moist and you also leave enough grass for photosynthesis and plant growth.

What causes shallow root growth?

Apart from improper watering and mowing practices, other factors can cause your lawn grass to grow shallow roots.

Compacted soil is one of the most common causes of an unhealthy lawn because it causes a very solid layer that is impenetrable and if nothing is done about it, your lawn will grow on compacted soil and continue being stressed.

Most of the time clay soil is always compacted because of its fine soil particles which can also hold water and prevent proper drainage, so the roots don’t grow deeper in search of water.

The best way to address this issue is to adjust your watering and mowing schedules to encourage deep root growth, aerate, and use compost as a topdressing in spring and fall.

After some time the roots will be able to break up the compaction as the soil conditions improve.

Your lawn may also have shallow root growth if you’ve planted shallow-rooted grasses.

Bentgrass and Kentucky bluegrass are some of the lawn grasses with the weakest root systems. Improving your soil’s roots conditions can help, but these grasses will never develop a deep root system.

Symptoms your lawn grass has unhealthy root systems

The most common problem with lawns is unhealthy roots and stressed roots lead to stressed plants that are more vulnerable to pests and diseases.

  • Weed infestation

If you have a weed infestation in your lawn this is a sign that there’s something wrong with your soil and your lawn’s roots are stressed.

Weeds mostly thrive in poor soil conditions, so you need to check the condition of your soil by doing a soil test. Also, check for compaction by trying to dig out a clump of grass.

If it’s very difficult your soil is compacted which also means it has a nutrient imbalance.

Consider aerating your lawn in spring or fall and add compost as a topdress.

Spraying herbicides is only a temporary solution, but mowing your lawn frequently will help stop the spread of the weed seeds so they can’t reproduce.

By practicing healthy lawn maintenance and with improved soil conditions, your lawn grass will grow thick and healthy which will choke out the weeds.

  • Wilting

If you’re walking on your lawn and you can see your footprints, it means your lawn is suffering from water stress. You can quickly solve this problem by watering your lawn thoroughly the next morning, but if you allow your lawn to stay wilted for many days, the roots will continue to wilt and die from lack of water.

Wilting can also be caused by overwatering making your lawn wilted and soggy which is a more serious problem.

If you overwater your lawn, allow the soil to dry as much as possible before using the 1-2-3-2-1 watering schedule to ensure you don’t over or underwater your lawn again, although roots can handle moisture better than a lot of moisture.

If your lawn gets overwatered from heavy rains, improve the drainage of your lawn by aerating and using compost to prevent oversaturation in the future.

  • Brown or yellow leaves

The most common cause of dead patches on your lawn is grubs that feed on your lawn’s roots during their larvae stage which causes severe stress on your lawn grass.

Dig up a patch on your lawn to help you identify the grub species and the best treatment, then apply preventative insecticides in spring and carry out curative measures in the fall.

Warm-season grasses tend to rejuvenate faster from dead patches than cool-season grasses because they grow faster through spreading. If your lawn is severely infested with grub, you can overseed your cool-season grass to help your lawn recover faster.

  • Circles pop up in the grass

If you notice mysterious grass circles also called fairly rings appearing on your lawn in your healthy-looking lawn, it’s a sign that there’s fungus in your soil. You may also find mushrooms growing in a circle.

The fungus in your soil will cause the circle of grass to be greener initially than the rest of the grass because there’s more organic matter in that circle that provides nutrients to the soil and more moisture.

However, as the fungus grows deeper into the soil it starts to deny the grass roots nutrients and moisture.

The best solution is to apply a fungicide on only the affected areas, but if it doesn’t work, you’ll have to dig up the circle and plant new grass.

Turfgrasses with Deep Root Systems

Grass category

Grass-type

Root system

Lawn care

Warm-season grasses

Bermuda grass

Has the deepest root system with roots that can grow up to 8 inches below the surface although most of the root system can go up to 12 inches.

Requires consistent mowing to help develop a deep root system

Zoysia grass

Significantly shorter root system than Bermuda grass, reaching only 2 inches deep. Has a thick and dense root system which makes it more efficient in absorbing water and nutrients from the topsoil.

Easy to maintain and takes 3-5 years to develop a thick lawn

Cool-season grasses

Perennial ryegrass

Has the deepest roots among the cool-season grasses with roots that are 2 inches deep. However, these roots behave like those for an annual which means they die every spring.

Germinates quickly but doesn’t fill well because it’s a bunch-forming grass and doesn’t repair bare spots easily.

Tall fescue

Has the deepest root system of all the cool-season grasses with roots that can grow up to2-3 inches deep making it the best drought-resistant cool-season grass.

A bunch-forming grass that doesn’t spread quickly or fill bare spots well, but can tolerate the shade but not heavy traffic.

Conclusion

Maintaining a healthy lawn is more about your long-term maintenance practices and by improving your soil you’ll allow the roots to support healthy and vigorous growth that will prevent weeds from invading your lawn and be more resistant to pests and diseases.

Also read

How High can Grass Possibly Grow before Folding Over?

References and sources

Grass Growth and Regrowth for Improved Management

Grass root Growth

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