Ornamental · Poaceae
Fountain Grass
Pennisetum alopecuroides
Tuck it into full sun and lean soil, and fountain grass arches up into a soft, plumed mound that carries the garden right through winter.
Full sun
Every 7–14 days
USDA 5–9
2–5 ft · 0.6–1.5 m
Overview
Fountain grass lives up to its name beautifully. The leaves rise and spill back over into a tidy mound, and come late summer the soft, bottlebrush plumes lift above the foliage and sway with every breeze. It's a warm-season clump-former in the grass family, comfortable across a wide band of cold-hardy ground from zone 5 to zone 9.
What makes it such a friendly choice is how little it asks of you. Once it has settled in, it brushes off drought, wants next to no feeding, and carries no serious pests along with it. The plumes open silvery to pinkish and the whole clump glows gold in fall, keeping its shape and color long after the first hard frosts.
The single thing to keep a gentle eye on is its knack for seeding itself around. Hardy fountain grass can self-sow into nearby beds and even slip out into wild ground, and its tender cousin, crimson fountain grass, behaves like a real weed in warm, dry regions. Snip the plumes before the seed drops and you'll have all the beauty with none of the bother.
Care
The short version: give it full sun and average, well-drained soil, water it faithfully until it's settled in and then mostly leave it be, and cut the whole clump down to the ground in late winter before fresh growth starts.
Light
Fountain grass is happiest in full sun, where it grows dense and stands tall and proud. It will put up with partial shade, but where the light runs short the stems soften and the whole clump tends to flop open.
Water
Water it faithfully through that first season while the roots find their footing. Once that's done it turns drought tolerant and gets along on rainfall in most gardens, though it does love soil that stays medium to wet, so a good deep drink during a long dry spell keeps it looking fresh.
Soil
Plain, well-drained soil suits it just fine, and it isn't the least bit fussy about pH. Steer clear of rich, heavily amended beds, since too much fertility grows floppy stems that lose the lovely fountain shape.
Temperature
This is a tough one, hardy across a wide span from about -20°F to 100°F (-29°C to 38°C). That cold-hardiness is exactly what lets it carry on as a true perennial all the way through zone 5.
Humidity
Everyday outdoor air is all it asks for, so there's no number to fuss over. Air moisture simply isn't a concern for a grass this rugged.
Feeding
This one is a low-feed plant, which is good news for anyone short on time. A light scattering of balanced fertilizer or a little compost in spring is plenty, and plenty of gardeners skip it entirely, since rich soil only nudges the clump toward flopping.
Pruning
Cut the whole clump back to a few inches above the ground in late winter or early spring, before the new growth pushes through. Where self-seeding worries you, just snip the plumes off in fall before the seed drops.
Repotting
Divide a clump every 2 to 4 years to keep it lively and full. When the middle dies out and bare ground rings the center, that's simply the plant letting you know it's ready for splitting.
Size & spacing
A clump grows 2 to 5 feet (60 to 150 cm) tall and roughly as wide. Give it that much elbow room so the fountain shape has space to arch over gracefully without crowding the neighbors.
When to plant
Fountain grass keeps time with the warm season, and that makes it wonderfully forgiving. Start seed indoors in late winter or set divisions out in spring once the chill has eased and the soil has warmed, and the plumes will turn up in late summer and linger through fall and into winter.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 8 to 10 weeks before last frost
- Plant: spring after last frost once soil has warmed
- Harvest: late summer into fall, plumes often persisting through winter
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Fountain grass is one of the healthiest plants you can grow, so most of its quirks come down to habit rather than disease. The few things that go astray tend to show up in the shape of the clump or in seedlings appearing where you never sowed them. Match what you're seeing below, and you'll find the fix is almost always an easy one.
Little seedlings turning up around the base
Those lovely plumes drop a generous amount of seed, and where winters stay mild that seed lives on to sprout come spring. That habit of self-seeding is what lets fountain grass spread where you didn't want it and slip out into wild ground. Don't worry, the cure is gentle: trim the plumes off in fall before they break apart, and tug or hoe the little volunteers while they're still small.
Fix:
- Cut off and remove flower plumes before seeds mature and shatter
- Pull or hoe volunteer seedlings while young
- Choose sterile or low-seed cultivars where available
A bare middle circled by healthy growth
After a few years, an older clump simply gives up in the middle and keeps growing only out at the rim. Take heart, this center die-out is nothing more than the plant aging, not a sign of any disease. Lift the whole thing in early spring, toss the tired core, and tuck the strong outer pieces back into the ground.
Fix:
- Dig and divide the clump in early spring
- Discard the dead center and replant healthy outer divisions
Stems splaying open rather than arching up
A happy fountain grass arches upward and tumbles back over, just like its name promises, so a sprawling, splayed clump is usually a quiet hint of too little sun or soil that's a touch too rich. Flopping traces back to shade and heavy feeding, which together coax out soft, weak growth. Shift it into full sun and go easy on the fertilizer, and the stems will firm right back up.
Fix:
- Move or plant in full sun
- Avoid heavy fertilizing and overly rich soil
Toxicity
Here's the reassuring part for pet owners: fountain grass is not poisonous to animals or people. The only thing to treat with a little care is the plant itself, since the leaf edges can be sharp and the bristly seed plumes carry barbed awns that can catch in fur or skin the way a foxtail does.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
A cat that nibbles a blade has nothing to fear, since nothing in this grass will poison it. The one detail worth a glance is the bristly seed head, because those barbed awns can snag in fur or work into skin the way a foxtail does.
Dogs Safe
A dog can happily chew the leaves with no risk of poisoning at all. Just keep a casual eye on the seedy plumes, since the small barbed awns can wedge between toes or slip into the ears.
Horses Safe
Horses can graze it without any harm. The mature seed heads are the only bother, carrying stiff awns that can irritate the mouth, so mowing or cutting it before it sets seed in a pasture is the kind thing to do.
Rabbits Safe
Rabbits can munch the leaves with no worry, and the soft spring growth is the part they go for first.
Livestock Safe
Cattle, goats, and sheep can all graze it with no toxic effect whatsoever. The only thing to mind is the sharp-edged blades and bristly seed heads, since the awns can pester the mouth once the plumes harden off.
Birds Safe
Birds face no danger here at all, and finches and other seed-eaters will happily work the ripe plumes right through fall and winter.
People Safe
There is nothing in this plant that can poison people. Slip on gloves when you cut it back, since the leaf edges are sharp enough to leave a paper-cut sting.
Not chemically poisonous, but the bristly flower and seed plumes carry tiny barbed bristles and awns that can act as a mild mechanical or foxtail-type irritant, and the leaf edges can be sharp; handle plumes with care around pets and children.
Varieties
A handful of fountain grass cultivars are worth getting to know, mostly grouped by size and plume color. These are the ones you're most likely to come across.
Hameln
A neat dwarf form that flowers a little earlier and shrugs off cold winters more easily than the plain species.
Little Bunny
The tiniest one of all, reaching only around 12 to 18 inches, which makes it a tidy choice for edging and small pots.
Moudry
Prized for its almost-black, purple plumes, but be aware it self-seeds more freely than any other cultivar and can turn into a nuisance.
Pennisetum setaceum 'Rubrum' (purple/crimson fountain grass)
A tender, burgundy-leaved relative grown as an annual where winters bite, but it goes seriously invasive in warm, dry regions and is best left out of those gardens.
How to propagate
Making more fountain grass is wonderfully easy, whether you split a clump you already have or sow the plain species from seed.
DivisionEasy
Early spring before new growth · One growing season
Splitting a clump is the simplest, most reliable way to make more fountain grass. Lift it in early spring before the new growth pushes up, discard any dead center, and break the healthy outer ring into chunks that fill back in over a single season. It's also the only way to keep a named cultivar true, since those won't come back the same from seed.
SeedEasy
Spring · One to two growing seasons
The plain species sprouts willingly from seed sown in spring, needing one to two seasons to fill out into a full clump. Just keep in mind that the named cultivars won't breed true this way, and seed-grown plants can self-sow hard enough to become a weed.
Myths
All fountain grass is the same and safe to plant anywhere.
Two quite different plants go by this one name. The hardy, clump-forming Pennisetum alopecuroides is the easygoing garden grass, while the tender Pennisetum setaceum, including 'Rubrum', is grown as an annual and runs wild in warm, dry places like California, Hawaii, and the arid Southwest. Even the hardy kind can self-seed and grow weedy, so make a habit to cut the plumes before the seed drops wherever spread is a concern.