All About Rhizome Grass (and why it’s awesome)

The way your lawn grows and spreads can seem almost like a mystery to those who don’t know anything about grass. But it’s no mystery at all, when you take a close look at it. In fact, it’s one of the many wonders of nature at work. In today’s article I’ll discuss Rhizome grass … how it grows, spreads in your lawn, and why I love this grass type.

Grasses first evolved around 55 million years ago at the end of the cretaceous period.

It’s actually possible to trace fossil ages based on the development of grass, and as grasses grew on the earth, they made the surrounding wildlife evolve to grow smaller. Mammals were now free to enjoy a new, consistent source of nutrients even if they couldn’t climb trees or reach leaves.

Large swaths of the world enjoy an ecosystem which is comprised primarily of grasses, like the American plains or the Asian steppe.

Today, many of us take grass for granted, but if you’ve struggled to get grass to grow, or have thin and bare patches in your lawn, you’ll be interested to learn about some of the ways grass spreads.

I’ll explain:

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What Are Stolons and Rhizomes?

There are two primary ways that grasses spread, through stolons or rhizomes.

The principals are very similar for both of these systems. The root system from the grass spreads out across the ground, then establishes a new blade of grass with its own root system that spreads further.

Some grass seed is specifically marketed as “self-spreading” or “self-repairing” because that type of grass spreads naturally, either through Stolons or Rhizomes.

But what exactly are they, and what is the difference between Rhizomes and Stolons?

Stolon Grass

Stolons are stems that produce nodes from which new plants form.

In essence, the grass plant sends out runners across the turf, and when these come into contact with soil, roots will grow and a new plant will develop and fill in that area.

Stolons are typical in warm season grasses, like St. Augustine grass or centipede grass.

Rhizome Grass

Rhizomes work in a similar way to Stolons, but Rhizome grass sends out their root system under the soil, with new plants taking root and growing where there is adequate moisture and sunlight.

Rhizomes are typical in cooler season grasses, like Kentucky bluegrass, though Bermuda grass has both Stolons and Rhizomes, which is one reason it’s so popular on golf courses.

Rhizome Grass vs Stolon Grass for Lawns

Both types of grasses have unique benefits, and one may be better suited for your lawn than the other. There are even some lawn grasses (like Zoysia grass) which spread by both rhizomes and stolons.

Stolon grass can withstand more inhospitable areas, like in hot, unforgiving climates.

Rhizome grass spreads very quickly and takes root to spread its grasses. This is a very good feature, as it will fill bare patches in your lawn very quickly, which is desirable in northern climates where there is a shorter growing season.

However, the growth and spreading habit of Rhizome grasses labels it an invasive species in areas where the grass has been introduced and is not native.

While I love using Rhizome grass types in lawns, and it’s great for creating a dense, green carpet of a lawn … keep in mind this spreading habit makes Rhizome grass quickly spread into garden beds if left unchecked.

Installing garden edging is enough to keep it out, however.

Definition of a Rhizome

A rhizome, more specifically, is a modified stem that comes off the bud at the crown zone (where the blade meets the ground).

It grows in three phases, downward, then lateral, and finally upward when it forms a new blade.

The stolon or rhizome grows horizontally until they turn upward to form a new shoot or continue with its horizontal growth.

Categories of Lawn Grasses

There are two other categories of Rhizome grasses which you can choose from when deciding what type of grass you want in your lawn or garden.

These are determinate and indeterminate.

Determinate Rhizome Grass

Determinate rhizomes spread in isolated patches, rather than dense mats. These include popular grass types like creeping red fescue and Kentucky bluegrass.

These grasses are so tough they can spread well even in highly compacted soils, making them excellent grass choices if you have clay soil in your yard.

Indeterminate Rhizome Grass

An indeterminate rhizome grass will spread at greater distances.

In other words they’ll keep growing and spreading laterally until they encounter an obstacle that stops them.

Indeterminate rhizome grasses are far more invasive. It’s more difficult to control them.

Quackgrass and Johnsongrass, as well as Bermuda grass are a few common indeterminate rhizome grass types.

Bermuda Grass has rhizomes and stolons, but it also falls into this category.

The Evolution of Rhizome Grasses

The evolution of rhizomes developed a key defensive mechanism in grasses because they were then less likely to be harmed if trampled upon.

This makes Rhizome grass perfect for a lawn that has to withstand children and pets. It’s a great choice for your lawn if you have big, active dogs.

Rhizome grasses are better able to endure the stresses, and if a bare patch arises in your yard, rhizomes are best equipped to fill those gaps in naturally.

When met with bare patches, grasses with deep rhizomes (determinate) will quickly fill in the area without assistance within a year.

How Rhizome Grass Lawns Save Homeowners Time

Usually when a homeowner sees bare patches in their yard, additional measures are needed to fill in the patchy grass.

From overseeding or applying specific fertilizers, and watering daily … these lawn repair efforts take money and they take time.

However, the strong rhizome systems of this kind of grass will put in the effort to fill in bare spots on their own.

After 9 months, rhizome lawn grasses can recover 70% of their bare ground.

As the homeowner, that is a lot less work falling to you to keep your lawn looking amazing.

Healthy Roots, Healthy Lawn

Grasses with some of the strongest root systems develop rhizomes.

As the grass takes root, their systems will grow deep into the ground which makes them well suited to withstanding the harsh drought conditions during summer’s hottest period.

Certain grasses that spread via stolon are considered weeds in many areas of the country. They spread far more slowly than grasses with rhizomes.

In fact, centipede grass has its name from the way the stolons cause the grass to spread. You can observe the stolons spread as the grass grows and establishes new roots.

When you fertilize in the spring, choose a fertilizer with a balance of nitrogen (leaf growth) and phosphorous (root growth) for your rhizome grass lawn to kick off the growing season right.

Keeping Your Rhizome Grass Under Control

As I’ve mentioned, the best quality of rhizome grass is how quickly it spreads.

But this can also be a problem if grass is left to grow into areas where you don’t want it.

To keep the grass out of garden beds, walkways, and other areas of the yard, you can put lawn edging into place.

There are many varieties of lawn edging, such as plastic or metal, or you can make custom lawn edging using concrete or brick to keep your grass contained.

Make sure the edges reach at least six inches below ground to keep the grass roots from spreading.

Metal edging is very durable, and ages to a nice patina. It’s what professionals use, and you can place it into the ground using a rubber mallet and pins. I’ve purchased some of this heavy duty steel edging from Amazon for one of my garden beds and it has held up great.

Mow-over lawn edging is my favorite type. Install it right into the ground, level with your grass. This way, as you mow the edge of your lawn your mower can ride on top of the edging with one wheel for a nice clean cut.

Mowing your lawn regularly will also prevent it from spreading as quickly.

Final Thoughts About Rhizome Grass in Lawns

Rhizomes are not unique to grasses, and they have many evolutionary advantages in other plants, just as they do in grass.

In other plants, Rhizomes comprise the main stem of the plant. Other plants develop stem tubers, which is the thickened part of the rhizome. These are high in starch and store nutrients for the plant.

In lotus plants and turmeric, these are edible. Turmeric is used either as a spice or dye once it is dried and ground.

Why I Love my Rhizome Grass Lawn

The type of grass you choose for your lawn will likely depend first and foremost on the climate you live in.

With that said, I recommend choosing a native lawn grass with a hardy and robust rhizome root system.

The roots of your grass determine its ability to withstand all manner of issues. From heat, to drought, to disease, and heavy traffic … a grass with strong healthy roots will hold up best.

Rhizome grasses grow in thicker, which makes your lawn more capable of crowding out weeds. This will save you a lot of money annually on pre-memergent and post-emergent weed control.

And when other lawns in your neighborhood start to fade and look dull in the dog days of summer, your lawn will stay green longer.

I use a blend of Tall Fescue and native rhizome grasses in my sandy New England lawn, and have loved the results once I began to over-seed with hardy rhizome grass seed.