How Deep Do Grass Roots Grow?


Do you know how deep grass roots grow so you can accurately deliver the nutrients they need?

The average turfgrass has its abundance of roots in the top eight inches of soil, but they don’t stop there.

There is much to learn about the roots of grass, so I put together this guide. Inside, I discuss the average length of grass roots and ways you can help them grow deeper for a healthier and stronger lawn.

Whether you are growing grass from seed or laying down sod, knowing how to optimize the root system will benefit your lawn and your home’s curb appeal!

How Long Are Grass Roots?

The depth of grass roots can reach as little as a few inches to as deep as two or even three feet, especially with mature lawns.

Any homeowner who has spent time digging in their yard can attest that most of those roots are close to the surface, but are unaware that grass roots can reach much further down when the lawn is maintained correctly.

parts of grass roots

When you plant grass seed, the roots will develop three or so inches deep before you see any growth from above the surface. This initial root growth helps stabilize the plant as the shoots grow. 

Most turf grasses found in yards are known as perennial (life cycle) such as:

  • Kentucky bluegrass
  • Ryegrass
  • Bermudagrass
  • Fescue

Because these plants continue to grow all year, or regrow after a dormant cold season, they have the ability to establish deep root systems.

The Importance Of A Healthy Root System In Grass

Without a supportive root system, your lawn will suffer. For grass to thrive, it needs to absorb water, oxygen, and nutrients from the soil. The longer and more spread out the roots, the more the grass can take in.

Deep roots also help the grass tolerate stresses, such as in times of drought because they have access to moisture lower in the ground, or extreme freezes as the deeper roots will not die off.

A sparse root system cannot hold the soil in place as well as a dense network of roots. Especially on hills or rolling terrain, a healthy root system can deter erosion during heavy rains, keeping your lawn looking lush.

For soils that are easy to compact, such as clay, roots help break pathways through the ground, which aid in water and oxygen penetration.

When older roots die off and decompose, they add organic matter to the soil that helps to retain moisture, which is very helpful if your soil is sandy. The decaying roots also add nutrients that actively growing grass can use for food.

Related | Can You Just Sprinkle Grass Seed On Your Lawn?

How To Make Grass Roots Grow Deeper

There are two main ways to get the roots of your grass to grow deeper: proper mowing and watering.

1. Mowing

Mowing “shocks” the grass into thinking it is under attack. The grass roots will automatically dig deeper and also spread sideways to combat the stress from cutting the blades and will search for space to fill in with more grass shoots so it can continue growing.

By mowing your lawn frequently (to the right height for your type of grass), you encourage the plant to expend its energy on this downward and sideways growth, and not on upward blade growth.

So, not only will mowing make your yard look tidy, it will eventually help turn your lawn into a thick and less weed-prone expanse more tolerant to adverse conditions.

TIP: Never cut off more than 1/3 the height from your grass during mowing. Cutting off too much can cause permanent damage to your lawn’s health.

Here are the suggested mowing heights for popular grasses:

  • Fine Fescue – 3 inches
  • Perennial Ryegrass – 3.5 inches
  • Kentucky Bluegrass – 3.5 inches
  • Tall Fescue – 4 inches
  • Zoysia – 1 to 2 inches
  • Bermudagrass – 1 to 2 inches
  • St Augustine – 3 inches

Related | Best Grass Shears For Cutting Your Lawn

2. Proper Watering

Regular deep watering of grass is critical to achieving a deep root system.

Daily watering, as is frequent with many sprinkler systems, often create shallow or more surface-oriented moisture that encourages roots to stay near the ground level to absorb the water.

By letting your lawn dry out some between waterings, it will encourage the roots to grow deeper in search of moisture. When you do water finally and give the lawn a super deep soak, the longer roots are rewarded for their efforts and grow even longer.

A good rule of thumb for watering grass is:

  • Once a week in spring and late fall
  • Twice a week in early summer and early fall
  • Three times a week in mid to late summer

Between one to two inches of water per session should suffice to soak well into the soil. A water gauge is a handy way to determine how much water you are laying down.

Homeowners with Zoysia grass should be aware that this variety of grass has a very short root system that reaches only a couple of inches into the soil, so deep soaks during watering is not necessary.

In Summary

It’s surprising to think just how far your grass’s roots can grow when given the proper care.

With just a bit of extra planning, you can encourage vigorous root development that will help your lawn look incredible while minimizing overall maintenance needs like fertilizing and weed control.

When you know how deep grass roots grow, you can start today to improve the health and beauty of your lawn!

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