How Fast Do Ornamental Grasses Spread?

Ornamental grasses come in a wide range of shapes, sizes, and varieties, and as a result, they can often spread at different rates. However, all ornamental grasses follow a few similar growth patterns that might help you get a better understanding of what to expect from the species you’re cultivating.

Ornamental grasses spread relatively fast. In most cases, they spread fastest during the hot summer months and remain dormant during the winter. Some ornamental grasses can grow as tall as 30 feet (9.14 meters) within a year, but not all of them grow this quickly.

The rest of this article will discuss how fast ornamental grasses spread in greater detail. It will also discuss the fastest and slowest growing grasses, so be sure to keep reading if you want to learn more.

Are Ornamental Grasses Invasive?

Many ornamental grasses are invasive, meaning they rapidly spread and grow across a land. This can be an issue if there isn’t enough space for the grass to grow and there are other plants close by. However, if a variety is planted in ample free space, it shouldn’t cause any issues.

Some examples of invasive ornamental grasses include:

When invasive ornamental grasses (and other invasive plants) occur naturally in the environment, they can cause a wide array of issues. This is because once they begin growing, they’re difficult to control or maintain. They can affect the soil, other plants, water supply, and the local community.

However, some gardeners will choose to plant invasive ornamental grass willingly, and before doing so, they must ensure they have adequate space to avoid the above problems.

Although many invasive ornamental types of grass begin growing slowly, the growth speed will increase as the years go by. 

For example, maiden grass grows slowly in its first year (generally reaching around a foot tall), but as the years go on, it will start growing faster.

What Are the Fastest Spreading Ornamental Grasses?

The fastest spreading ornamental grasses include bamboo, fountain grass, and blue lyme grass. For example, fountain grass can reach as wide as four or five inches (10-13 centimeters) within the first few months of planting. This is especially likely to occur if it’s planted in the spring.

It’s important to note that there’s a virtually endless array of ornamental grasses available today, so it’s difficult to say which ones are the fastest spreading. 

However, it is possible to recognize some popular ones that spread and grow quickly, so let’s discuss them in greater detail below!

Bamboo

When people think of bamboo, they might not realize that it’s considered a type of grass. Many people assume it’s just a different kind of plant, but, in fact, it is a type of ornamental grass! Moreover, bamboo is considered the fastest growing plant in the entire world.

There are two main types of bamboo:

  • Running
  • Clumping

Running bamboo spreads and grows more quickly than clumping bamboo and is considered highly invasive (like many other types of ornamental grass). For this reason, many people like to avoid planting running bamboo in their gardens.

Clumping bamboo doesn’t spread as rapidly as running bamboo, so it’s less invasive. However, it can still grow fast, so you won’t have to wait too long to see it shooting up. It can grow to around three or four feet (0.91-1.21 meters) in its first year.

Bamboo can grow many inches in the space of a day, so if you’re looking for something extremely fast-growing, look no further!

Fountain Grass

Fountain grass is a popular ornamental grass choice because it’s easy to maintain once planted. On top of that, it gives every garden a fresh and bright look. Luckily, this grass does well in all kinds of soil types. 

However, the best soil is well-drained. It also prefers warm, sunny weather, so you should plant it somewhere that receives lots of natural sunlight for the best results.

Although fountain grass is a relatively fast-growing ornamental grass, it will only begin to grow once the soil has warmed up. So, it may be slow in the beginning. But once the soil heats up enough, it will begin to grow more quickly.

Blue Lyme Grass

Blue lyme grass is a popular choice because of its rare, vibrant blue color. Because of its bright blue foliage, it’s an excellent choice if you want something fast-growing and colorful at the same time!

However, this grass is invasive and spreads rather quickly, so you should only plant it if you’re sure you have adequate space for it. If you plant it near other plants, it’s likely to cause significant damage and be challenging to control. 

This grass grows best (and fastest) in full sun, but partial shade is acceptable.

Ravenna Grass

Ravenna grass, also known as elephant grass, is a prevalent hardy grass. It can spread around five feet (1.52 meters) wide and 12 feet (3.66 meters) tall, so it’s undoubtedly going to impact any garden in which it finds itself positively!

Since it is hardy, it can tolerate many environments. It is tolerant of frost, but it’s also tolerant of drought. Although it’s a hardy plant, Ravenna grass will grow and spread most quickly in warm temperatures and well-drained soil.

Like with other ornamental grasses, you should be cautious when planting Ravenna because it can be invasive and cause some problems to the surroundings.

What Are the Slowest Growing Ornamental Grasses?

Some of the slowest growing ornamental grasses include mondo grass and molinia. For example, mondo grass is so slow-growing that it doesn’t require much maintenance and rarely needs to be mowed or pruned. 

Now, let’s take a closer look at some examples of slow-growing ornamental grasses.

Mondo Grass

As mentioned briefly, mondo grass grows relatively slowly, so it doesn’t need much maintenance. It remains green throughout the year if it’s planted in a place with warm weather. However, it’s not fully evergreen in areas with colder weather.

Dwarf mondo grass spreads around four inches (10 centimeters) wide, and it usually takes three or four years to reach this point. Because of this, it’s easier to control than many faster-growing invasive types of grass.

Since it is a warm-season grass, it will grow best (and slightly quicker) in a warmer climate.

Molinia (Purple Moor Grass)

Molinia (also known as purple moor grass) is a beautiful, slow-growing ornamental grass native to Europe and Asia. As you may have guessed from the name, it often has a purple tinge and gives any garden a hint of color.

It generally grows to about three or four feet (0.91-1.21 meters) tall, so it’s a relatively long type of grass plant. Molinia grass grows best in warm weather and full sun, but partial shade should be okay. It can take several years for molinia to reach its full height, so you’ll undoubtedly need some patience for this ornamental grass!

Hakone Grass

Hakone grass is native to Japan and is a slow-growing perennial. If you’re worried about an invasive plant, you don’t have to worry about Hakone. Although it can spread a little, it is never considered invasive and shouldn’t cause damage to the surroundings.

This grass plant produces large bright green leaves and unlike many other types of ornamental grass, this one can grow in the shade. It doesn’t spread quickly, nor does it spread very much. It can usually reach around 24 inches (61 centimeters) wide, but it can take years to get to this point.

How To Help Ornamental Grass Grow Faster?

To help ornamental grass grow faster, you should make sure you grow it in the required conditions. Each type of grass has specific needs, so you should research them before planting. You should also make sure your grass is getting enough water. 

Another element to consider is pruning your ornamental grass (if required). Pruning is essential because it gets rid of old, dead grass and allows new healthy grass to grow in its place. 

All deciduous ornamental grasses need to be pruned or cut back every year. The best time to do this is in early spring, before new growth comes in. 

What Is the Easiest Ornamental Grass to Grow?

The easiest ornamental grass to grow is one that requires the least amount of maintenance once planted. Since evergreen plants require less pruning than deciduous ones, they are generally easier to grow and maintain. A common type of evergreen ornamental grass is Mexican feather grass.

Although you don’t need to prune evergreen ornamental grasses as much as deciduous ones, you may still need to cut them back every few years for aesthetic reasons. Even still, they’re easier to maintain. 

Plus, Mexican feather grass grows at a moderate pace, so it’s easier to control than fast-growing grasses that are invasive and difficult to manage.

Conclusion 

Ornamental grasses spread at different rates depending on the type of grass in question. Faster growing (and spreading) ornamental grasses include:

  • Bamboo
  • Fountain grass
  • Blue lyme grass

Bamboo, for example, can grow many inches in just one day.

However, other ornamental grasses are more slow-growing, including mondo grass and molinia grass. With slower-growing grasses, it can take several years before they reach their maximum heights and widths. 

To ensure your ornamental grass thrives, you should grow it in the appropriate weather and soil conditions (these vary from plant to plant).

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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