Ornamental · Poaceae
Fountain Grass
Pennisetum alopecuroides
Give it full sun and lean soil, and fountain grass arches up into a soft, plumed mound that keeps the garden going all winter.
Full sun
Every 7–14 days
USDA 5–9
2–5 ft · 0.6–1.5 m
Overview
Fountain grass really lives up to its name. The leaves arch up and spill back over into a tidy mound, and come late summer the soft, bottlebrush plumes lift above the foliage and catch every passing breeze. It's a warm-season clump-former in the grass family, happy across a big band of cold-hardy ground that runs from zone 5 to zone 9.
So what makes it such a workhorse? It barely asks for anything. Once it's settled in, drought rolls right off it, it wants next to no feeding, and it brings no serious pests with it. Those plumes open silvery to pinkish and the whole clump goes gold in fall, keeping its shape and color well past the first hard frosts.
The one thing to stay on top of is its knack for seeding itself around. The hardy fountain grass can self-sow into nearby beds and even slip out into wild ground, and its tender cousin, crimson fountain grass, is a real weed in warm, dry regions. But clip the plumes before the seed drops and you keep all the looks with none of the trouble.
Care
The short version: it wants full sun and ordinary, well-drained ground, steady water while it settles in, and after that not much at all, plus one big haircut down to ground level in late winter, ahead of the new growth.
Light
Fountain grass wants full sun if you want it at its best, where it fills out dense and stands tall. It'll put up with partial shade, but in too little light the stems turn soft and the whole clump flops open.
Water
Keep it watered regularly through that first season while the roots dig in. After that it's drought tolerant and coasts along on rain in most places, though it likes soil that stays medium to wet, so a good deep soak during a long dry spell keeps it fresh.
Soil
Average, well-drained soil suits it just fine, and pH isn't something it frets over. Steer clear of the rich, heavily amended beds, since too much fertility grows floppy stems that won't hold the fountain shape.
Temperature
It's tough across a wide range, hardy from roughly -20°F to 100°F (-29°C to 38°C). That cold-hardiness is exactly what lets it grow as a true perennial all the way through zone 5.
Humidity
Plain old outdoor humidity is all it asks for, so there's no number to chase here. Air moisture just isn't a thing for a grass this rugged.
Feeding
This is a low-feed plant. A light dose of balanced fertilizer or a bit of compost in spring covers it, and plenty of gardeners skip even that, since rich soil only makes the clump flop.
Pruning
Cut the whole clump back to a few inches above the ground in late winter or early spring, before the new growth pushes up. Where self-seeding worries you, snip the plumes off in fall before the seed drops.
Repotting
Split a clump every 2 to 4 years to keep it going strong. When the center dies out and bare ground rings the middle, that's the plant telling you it's overdue for dividing.
Size & spacing
A clump runs 2 to 5 feet (60 to 150 cm) tall and about as wide. Give it that much room to spread so the fountain shape can arch over without crowding whatever's next to it.
When to plant
Fountain grass works on the warm season. Start seed indoors in late winter, or pop divisions out in spring once the cold's gone and the soil has warmed up, and then the plumes show up in late summer and stick around 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 hardly ever gets sick, so its problems are mostly about how it grows rather than any disease. The few things that do go sideways turn up in the shape of the clump or in seedlings showing up where you never planted them. Match what you're seeing below and the fix is usually pretty simple.
Little seedlings springing up all around the clump
Those plumes look lovely, but they drop a ton of seed, and where winters stay mild that seed lives to sprout come spring. That's how self-seeding lets fountain grass go weedy and slip out into wild ground. So clip the plumes off in fall before they shatter, and yank or hoe the volunteers while they're still tiny.
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, hollow middle with a ring of green around it
Once every few years an aging clump simply gives up in the middle and only keeps going around the rim. That center die-out is just old age, not anything you caught or did wrong. Dig the whole thing up in early spring, toss the dead core, and replant the good outer pieces.
Fix:
- Dig and divide the clump in early spring
- Discard the dead center and replant healthy outer divisions
Stems splaying open instead of arching up
The whole point of a fountain grass is that it arches up and tumbles over like its name suggests, so a sprawling, splayed clump is usually a sign of too little sun or soil that's too rich. Flopping traces back to shade and heavy feeding, since both push out soft, floppy growth. Shift it into full sun, back off the fertilizer, and the stems stiffen up again.
Fix:
- Move or plant in full sun
- Avoid heavy fertilizing and overly rich soil
Toxicity
Here's the good news for pet owners: fountain grass is not poisonous to animals or people. The only thing to handle carefully is the plant itself, since the leaf edges can be sharp and the bristly seed plumes carry barbed awns that can snag in fur or skin like a foxtail.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
A cat that nibbles a blade won't get poisoned by anything in this grass. The bristly seed head is the part to watch, since those barbed awns can snag in fur or work their way into skin the way a foxtail does.
Dogs Safe
Chewing the foliage is harmless for a dog. Just keep an eye on the seedy plumes, because those little barbed awns can wedge between toes or get into the ears.
Horses Safe
Horses can graze it without any harm. The only real bother is the mature seed heads, whose stiff awns can irritate the mouth, so mowing or cutting it before it sets seed in a pasture is the safe bet.
Rabbits Safe
Rabbits eat the leaves with no trouble, and the soft spring growth is the part they go for first.
Livestock Safe
Cattle, goats, and sheep can all graze it without any toxic effect. The sharp-edged blades and bristly seed heads are the only thing to mind, since the awns can bug the mouth once the plumes harden off.
Birds Safe
Birds have nothing to fear here, and finches and other seed-eaters love working the ripe plumes right through fall and winter.
People Safe
Nothing in this plant is poisonous to people. Just pull on gloves before 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 knowing, sorted mostly by size and plume color. These are the ones you'll come across most.
Hameln
Hameln's the tidy dwarf of the group. It comes into bloom sooner than the plain species and shrugs off a cold winter more reliably too.
Little Bunny
Looking for something truly tiny? This one stays around 12 to 18 inches at most, so it slots nicely along an edge or into a small pot.
Moudry
People grow it for those near-black, purple plumes, but fair warning: it self-sows more heavily than any of the other cultivars and can quickly wear out its welcome.
Pennisetum setaceum 'Rubrum' (purple/crimson fountain grass)
Here's the tender, burgundy-leaved cousin that cold-climate gardeners grow as an annual. Where the climate runs warm and dry, though, it turns into a serious invader, so those gardens should skip it entirely.
How to propagate
Fountain grass is easy to make more of, whether you split an existing clump or sow the plain species from seed.
DivisionEasy
Early spring before new growth · One growing season
Division is the easy, reliable way to make more fountain grass. Dig the clump in early spring before the new growth pushes up, ditch 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, because those won't grow back the same from seed.
SeedEasy
Spring · One to two growing seasons
The plain species sprouts readily from seed sown in spring, then takes one to two seasons to build a full clump. Watch out, though, since the named cultivars won't come true this way and seed-grown plants can self-sow hard enough to become a weed.
Myths
Every fountain grass is the same and fine to plant wherever you like.
Two very different plants go by this one name. The hardy, clump-forming Pennisetum alopecuroides is the well-mannered garden grass, while the tender Pennisetum setaceum, 'Rubrum' included, gets grown as an annual and runs wild in warm, dry spots like California, Hawaii, and the arid Southwest. And even the hardy one can self-seed and go weedy, so cut the plumes before the seed drops anywhere spread is a worry.