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How to Grow Purple Fountain Grass, an Ornamental Grass

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.


What is Purple Fountain Grass?

Purple fountain grass (Pennisetum setaceum ‘Rubrum’) is a cultivar of a grass that is native to Africa, the Middle East and Southwest Asia. The species grass is invasive. Like many hybrids, Rubrum’s seeds are sterile. Sterile seeds and slower growth make this grass less invasive than its parent.

Both the species grass and Rubrum grow in a clump with long, arching foliage, giving them the appearance of water spraying from a fountain, hence the name “fountain grass.”

Purple fountain grass is only hardy in zones 9 – 10. It is grown as an annual in temperate zones or in a container and brought indoors during the winter.

This clump-forming grass grows rapidly to reach 3 – 5 feet tall and 2 – 4 feet wide in a single season. The leaves are purple or burgundy red. The flowers are also red and shaped like a bottle brush. They can be up to 12 inches in length. Bloom time is July through October.

The flowers are red and can be up to 12 inches in length.

The flowers are red and can be up to 12 inches in length.

How to Grow Purple Fountain Grass

Purple fountain grass is purchased as plants from a nursery. The seeds are sterile, so it cannot be grown from seed.

The grass grows best in full sun. It will tolerate a little shade, but won’t reach its full size in shaded conditions. You can grow it as a specimen plant or massed together. If you are planting more than one grass in a bed, plant them 3 – 5 feet apart to allow for their 2 – 4 feet width.

Purple fountain grass will grow in almost any kind of soil as long as it drains well. It grows best in rich, loamy soil. When grown in poor soil, add a balanced slow release fertilizer when you install the plants to help them grow and bloom their best.

Water the plants well when you first plant them, then twice a week until they are established. After that, you won’t need to water except during periods of drought. These plants are drought-tolerant.

This grass can be grown in containers alone or as part of a mixed planting.

This grass can be grown in containers alone or as part of a mixed planting.

How to Grow Purple Fountain Grass in a Container

Purple fountain grass grows well in containers. It can be grown alone in a container or as part of an attractive grouping of annual flowers.

Because it is a large plant, you will need a large container, at least 3 gallons, preferably larger. Make sure your container has a drainage hole so that your grass doesn’t sit in water.

You can use regular potting soil. Most potting soil these days comes with slow release fertilizer already in it so there will be no need to fertilize your plant.

Purple fountain grass loves full sun but the heat of the sun will dry out the soil in your container very quickly. Water it daily or every other day.

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In the fall before your first frost, you will need to bring your container indoors, either into a greenhouse if you have one or into your home. You can treat it like a houseplant during the winter. Place the container in your sunniest window, preferably one that faces south. Water regularly.

Or you can cut your grass down to about 3 inches and store it in your basement watering it about once a month. The plant will remain dormant until you put it outdoors in the spring.

Whether grown as a houseplant or dormant in your basement, you can bring your grass back outdoors in the spring after your last frost.

Purple fountain grass can be used in massed plantings.

Purple fountain grass can be used in massed plantings.

How to Divide Purple Fountain Grass

If you live in a warm area where purple fountain grass grows as a perennial or if you are growing it in a container and it has outgrown its container, you can divide your grass. The best time to divide your grass is when it is dormant.

In warmer areas, you will want to divide it in the fall before it achieves full dormancy. Using a garden spade, dig up the entire clump of grass. Then use sharp garden shears to cut the clump into 2 or 3 pieces. Cut away any dead leaves or roots and discard them. Replant your divisions 3 – 5 feet apart and water well, then twice a week as they settle into their new homes.

If you are growing your grass in a container, you can divide it in the fall when you bring it indoors. Remove the clump from its pot. Using sharp garden shears, cut the clump into 2 or 3 pieces. Remove any dead roots or leaves. Replant your divisions into new containers with fresh soil that are at least 3 gallons in size. Put the containers in a sunny window, preferably facing south and water regularly.

© 2020 Caren White


Caren White (author) on December 31, 2020:

I agree! It adds height and color.

Abby Slutsky from America on December 30, 2020:

It looks very nice in a container with other flowers.

Caren White (author) on December 29, 2020:

I'm not usually a fan of ornamental grasses, but I love this one in mixed plantings in containers.

Peggy Woods from Houston, Texas on December 29, 2020:

We see quite a bit of this grown in our area of Houston. There is a nearby medical campus where they use a lot of it along with other landscaping.

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