By Erin Marissa Russell
Ready to learn all about how to plant and care for purple fountain grass? This showstopping plant can be grown outdoors year round by those in USDA Plant Hardiness Zones 9 and 10. Purple fountain grass can grow to reach a height of between three and five feet tall, with a spread of two to four feet.
Purple fountain grass produces its feathery plumage in late summer and fall. You’ll see this plant used frequently in dried flower arrangements because of the beauty of its plumes.
Purple fountain grass is adaptable to a variety of soil conditions, as long as the soil gets good drainage. It thrives best in loamy soil, though.
Choose a spot in your garden that gets full sun to plant your purple fountain grass. Remember that full sun means at least six hours of direct sunlight each day. Though purple fountain grass will thrive best in full sun, it will tolerate a bit of light shade if needed.
Start seeds indoors in containers. Fill your containers with fresh, new potting soil. Then sprinkle the purple fountain grass seeds on top. Just a dusting of soil on top of the seeds is plenty. Water your freshly planted seeds until the soil in the container is evenly damp.
If your seed starting containers come with a plastic lid or dome, place this on top of the container. If not, you can cover the seeds with a plastic bag that has a few slits cut into it to allow oxygen to reach the seeds.
Once seedlings have two sets of new leaves, they should be transplanted into larger containers so they can spread out a bit. In springtime, harden off the plants before moving them into the outdoor garden. You can learn more about this process from our article How and Why to Harden Off Seedlings Before Moving Outdoors.
You may have heard that purple fountain grass is drought tolerant, and this is certainly true of established plants. However, you’ll need to water your purple fountain grass while it is getting established. Give the plants about an inch of water once or twice per week, and let the soil dry out completely in between watering sessions.
There’s a simple test you can do to determine whether the soil is still moist or dry. Just insert a finger into the soil about an inch deep. Does the soil feel damp to the touch? Does it cling to your skin? If the answer to either of these questions is yes, the ground is still damp and it isn’t yet time to water your purple fountain grass again. You should water the grass again when the soil is dry to the touch and does not stick to your skin.
Once plants are established, you won’t need to water them at all if you live in a region that gets occasional rain. If you live in a dry area, though, or an especially hot area, you should water your purple fountain grass occasionally to help it through these conditions.
You can grow purple fountain grass even in poor soil, but the plants should be given fertilizer while they are flowering because they need extra nutrition during this time. During their flowering period, which is usually the summer, use a general purpose slow release fertilizer monthly, following the manufacturer’s directions for dosage and instructions.
Purple fountain grass can be propagated either by division or from seed. Division is more commonly used because it is simpler and more likely to be successful, plus you don’t have to wait for seeds to sprout and plants to become established.
To propagate purple fountain grass by division, begin by gently digging up the plant, roots and all, when it is going dormant at the end of its growing season. Use a clean, sterilized cutting tool with a sharp edge to divide your purple fountain grass into two or more clumps, each with plenty of healthy roots and foliage. Pick off and dispose of any dead or damaged foliage and roots. Put the newly divided purple fountain grass into the ground in its new spots immediately, and water well to help the soil settle around it.
Though it’s not quite as quick and easy, you may choose to propagate new purple fountain grass from seed. You can collect the seeds once they have dried on the plant, usually in the fall. Remove the entire stem, and bring the flowering stalk to a dry, cool place so the seeds can dry completely. You can sow the seeds into containers immediately and let them grow until next spring when they can be transplanted into the outdoor garden, or you can save the seeds to plant next spring.
The right time to prune your purple fountain grass is at the end of winter or beginning of spring, before the plant starts putting out new growth. Cut the grass back substantially to encourage new growth and allow air and sunlight to circulate around the plant. Also remove any dead or damaged foliage at this time.
At any time of year, you can prune lightly for a touchup. Simply remove any dead foliage and lightly reshape the grass as needed.
Whenever you prune, you should use clean, sterile gardening shears. You can sterilize your shears by soaking them in a mixture of half alcohol and half water for five minutes. Then rinse the shears under clear running water and let them air dry.
You can grow purple fountain grass year-round even outside zones 9 and 10 if you overwinter the grass indoors. Start by cutting the grass back until it is about three inches tall. (The plants won’t look especially pretty over the winter, but they’ll spring back to life when warmer weather returns.)
Then gently dig up your purple fountain grass, roots and all, taking care not to damage the plant or its roots. Move the purple fountain grass into a container so it can be moved into a more protected location during the cold season.
Purple fountain grass has a shallow root system that is susceptible to damage from freezing temperatures. Store the plants over the winter in a cool place where they will get a moderate amount of light. Keep the plants watered over the winter, but do not let them get oversaturated. Also do not allow the soil to dry out.
Rust Fungus: This disease results from excess moisture or humidity in the environment. You can help prevent rust fungus by spacing purple fountain grass several feet apart so they have plenty of room to breathe. Remember that the spread of mature plants is two to four feet wide.
The number one contributor to rust fungus is overhead watering. Plants can only absorb and use the water that gets to their roots, so you should always water at the base of the plant. It also helps to do your watering early in the morning so excess moisture will be evaporated by sunshine.
Rust fungus causes speckled patches on the foliage that is typically rust-colored but may also be brown, orange, yellow, red, or even purple. The spots are tiny, arranged similarly to freckles. Just one leaf can have dozens of rust spots or even up to 100.
The good news is that rust fungus does not normally affect the plant’s growth or cause any damage. But if the disease is severe, you may see curled or withered leaves, or leaves may drop from the plant completely. As a preventive treatment or to cure rust fungus, you can sprinkle plants with sulfur each week.
Slugs and Snails: Slugs and snails are notorious for the damage they can do to a garden, leaving behind ragged holes and chewed areas on your plants. You can tell for sure where a slug or snail has been by checking for the slimy, silvery trails they leave behind. These will be most evident early in the morning, because slugs and snails do their feeding at night, and the trails will dissipate throughout the day.
There are lots of ways to defend your garden against slug or snail damage. One of the most common is sprinkling diatomaceous earth around the affected plants. The jagged, ragged edges of diatomaceous earth will cut into the slug or snail’s soft body as it tries to pass over the barrier, discouraging the mollusks away from the plant entirely. For more information, check out our article How to Protect Seedlings From Slugs and Snails. It explains several ways to keep slugs and snails at bay, and the last section explains how to use copper tape and plastic food containers to make a super effective snail and slug deterrent.
Not only is purple fountain grass beautiful—it’s also extremely low maintenance. In some climates, you won’t need to water the plants at all, and they’re accepting of a wide variety of soil types. Rust fungus and slugs and snails are the only real potential problems you can expect to encounter with purple fountain grass. Even better, both these issues are easy to address. Why not add some of the fabulous fronds of purple fountain grass to your garden?