Ornamental · Poaceae
Fountain Grass
Pennisetum alopecuroides
Set it in full sun and lean soil, and fountain grass throws up arching blades that cascade into a soft, plumed mound holding its shape clear through winter.
Full sun
Every 7–14 days
USDA 5–9
2–5 ft · 0.6–1.5 m
Overview
The name fits the plant exactly. Narrow blades shoot upward then bend and spill back over themselves into a neat mound, and by late summer soft bottlebrush plumes lift clear of the leaves and sway with every breeze. This is a warm-season clump-former in the grass family, hardy across a broad band of cold country from zone 5 through zone 9.
Its real strength is how little it demands. Once the roots have taken hold it brushes off drought, asks for next to no feeding, and carries no serious pests with it. The plumes unfurl silvery, blushing toward pink, while the whole clump goes gold in fall and keeps that form and color well past the first hard frosts.
The single thing to mind is its tendency to scatter seed and sow itself around. Hardy fountain grass can seed into the beds nearby and slip off into wild ground, and its tender relative, crimson fountain grass, runs amok as a weed in warm, dry regions. Clip the plumes off before the seed lets go and you keep every bit of the look without the headache.
Care
The short version: give it full sun and average, well-drained soil, water it regularly until it's established and then mostly leave it alone, and cut the whole clump to the ground in late winter before new growth starts.
Light
Fountain grass looks its sharpest in full sun, where the blades grow thick and stand tall. It tolerates partial shade, but starved of light the stems turn soft and the whole clump splays open.
Water
Keep it watered through that first season while the roots dig in. Past that it turns drought tolerant and lives on rainfall in most places, though soil kept medium to wet pleases it most, so a deep soak during a long dry stretch keeps the blades looking crisp.
Soil
Average, well-drained soil suits it just fine, and pH doesn't trouble it. Steer clear of rich, heavily worked beds, since too much fertility grows limp stems that can't hold the fountain shape.
Temperature
It's hardy across a sweeping range, holding up from roughly -20°F to 100°F (-29°C to 38°C). That tolerance for cold is what lets it stand as a true perennial all the way through zone 5.
Humidity
Plain outdoor air moisture covers everything it needs, so there's no target to hit. For a grass this tough, humidity simply doesn't register.
Feeding
This is a low-feed plant. A light scattering of balanced fertilizer or a little compost in spring is more than enough, and plenty of gardeners skip it entirely, since rich soil only sets the clump flopping.
Pruning
Shear the entire clump down to a few inches above the soil in late winter or early spring, before the new blades push through. Where self-seeding worries you, clip the plumes off in fall before the seed drops.
Repotting
Split a clump every 2 to 4 years to keep it growing strong. When the middle dies out and bare ground rings the center, that's the plant telling you it's past due for dividing.
Size & spacing
A clump stands 2 to 5 feet (60 to 150 cm) tall and spreads about as wide. Leave it that much elbow room so the arching fountain shape can spill over without crowding what's planted beside it.
When to plant
This grass keeps a warm-season clock. Sow seed indoors in late winter, or plant divisions out in spring once the chill has lifted and the soil has warmed, and the plumes show up in late summer, lingering through fall and on 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
Disease almost never touches fountain grass, so its troubles come down to behavior rather than sickness. The handful of things that do go wrong reveal themselves in the clump's shape or in seedlings cropping up where you never sowed any. Match the symptom below and the cure is usually straightforward.
Stray seedlings sprouting in a ring around the parent clump
Those soft plumes look harmless, yet each one drops a heavy load of seed, and where winters stay mild that seed lives to sprout come spring. That self-seeding is exactly how the grass slips into weediness and even creeps off into wild ground. Snip the plumes away in fall before they shatter, then yank or hoe the young volunteers while their roots are shallow.
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 hollow, dead middle with a living ring of blades around it
After a few seasons an aging clump simply gives out at its heart and keeps throwing up blades only along the rim. That center die-out is age, plain and simple, not rot or blight. Lift the entire crown in early spring, toss the lifeless core, and tuck the vigorous outer pieces back into the ground.
Fix:
- Dig and divide the clump in early spring
- Discard the dead center and replant healthy outer divisions
Blades splaying flat instead of arching up like a fountain
The clump is supposed to leap upward and cascade back over itself, so when it sprawls out wide and limp the cause is almost always shade or soil that's too rich. Flopping traces straight back to low light and heavy feeding, both of which grow soft, weak stems. Shift it into full sun, hold back on the fertilizer, and the blades stiffen up again.
Fix:
- Move or plant in full sun
- Avoid heavy fertilizing and overly rich soil
Toxicity
Good news for pet owners: fountain grass is not poisonous to animals or to people. The only part that calls for a careful hand is the plant itself, since the leaf edges can slice and the bristly seed plumes carry barbed awns that catch in fur or skin the way a foxtail does.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
A cat that bites off a blade faces no poison at all. The one part to watch is the bristly seed head, where those barbed awns can snag in fur or burrow into skin the way a foxtail does.
Dogs Safe
Chewing the foliage poses no poisoning risk to a dog. Keep watch on the seedy plumes, since the tiny barbed awns can wedge between toes or work down into the ears.
Horses Safe
A horse can graze it without any harm. The ripened seed heads are the lone bother, their stiff awns prickling the mouth, so cut or mow the clump before it sets seed in a pasture.
Rabbits Safe
The blades are safe for rabbits to eat, and the soft new spring growth is the part they go for first.
Livestock Safe
Cattle, goats, and sheep can graze it with no poisoning to fear. Only the sharp-edged blades and bristly seed heads warrant care, since the awns can prick the mouth once the plumes have hardened off.
Birds Safe
Nothing here threatens birds, and finches along with other seed-eaters often pick the ripe plumes apart through fall and winter.
People Safe
For people there is nothing toxic in this plant. Pull on gloves before cutting it back, because the leaf edges are keen 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, mostly told apart by size and the color of the plumes. These are the ones that turn up most often.
Hameln
A tidy dwarf selection that flowers ahead of the straight species and weathers hard winters with less trouble.
Little Bunny
The runt of the group, reaching only about 12 to 18 inches, which suits it well for edging beds and tucking into small pots.
Moudry
Prized for plumes so dark they read nearly black-purple, though it throws seed harder than any other cultivar and can turn into a pest.
Pennisetum setaceum 'Rubrum' (purple/crimson fountain grass)
A frost-tender relative with burgundy blades, treated as an annual in cold zones but turning aggressively invasive in warm, dry country where it has no place in the garden.
How to propagate
Fountain grass takes easily to propagation, whether you split a standing clump or sow the plain species from seed.
DivisionEasy
Early spring before new growth · One growing season
Splitting a clump is the standard route to more fountain grass. Lift it in early spring before fresh blades push up, discard any dead core, and break the living outer ring into chunks that fill back out within a single season. It's also the only way to keep a named cultivar true, since those refuse to come back the same from seed.
SeedEasy
Spring · One to two growing seasons
The straight species sprouts readily from seed sown in spring, needing one to two seasons to build a full clump. Tread carefully here, since the named cultivars won't breed true this way and seedlings can self-sow hard enough to become a weed.
Myths
All fountain grass is the same and safe to plant anywhere.
The name covers two plants that behave nothing alike. Hardy, clump-forming Pennisetum alopecuroides is the mannerly garden grass, while frost-tender Pennisetum setaceum, 'Rubrum' included, gets grown as an annual and bolts wild in warm, dry places like California, Hawaii, and the arid Southwest. Even the well-behaved kind can sow itself around and turn weedy, so cut the plumes before the seed drops anywhere spread worries you.