Purple fountain grass
Cenchrus x advena 'Rubrum' (formerly Pennisetum setaceum 'Rubrum') · Popular
Arching, burgundy-purple leaves and long, nodding, rose-red foxtail plumes from midsummer to frost.
- Size
- 4 ft tall, 2½ ft wide
- Zones
- 9 to 10
- Light
- Full sun
- Flowers
- Late June to mid October
- Pets
- Not checked
- Job in a bed
- Accent
A bed built around purple fountain grass
The planner designed this bed around purple fountain grass when this page was made: a 12 × 6 ft (3.7 × 1.8 m) naturalistic planting in zone 9, full sun. It chose the other plants from the 434 that suit those conditions, and says below why purple fountain grass stands where it does.
The plants
- 1 Purple fountain grass × 3, red
- 2 Woodland strawberry × 28, white
- 3 October daphne × 5, pink
- 4 Purple coneflower × 3, purple
- 5 Inkberry 'Gem Box' × 1, dark green leaves
- 6 Spring starflower × 5, blue
Why this plant
- The only plumes. The others are open bowls, dense clusters and daisies. Shape reads at a distance, where colours blur.
- The only red. The one hot colour: every other flower here is cool or neutral.
- Part of the bed's structure. Shrubs and grasses keep their shape when the perennials die down. So does inkberry 'Gem Box'.
Why here
- Anchors a back corner. At 4 ft it is the tallest plant here, and the tallest close the ends of the bed, where they stand in front of nothing.
- A step in the back row. Next to inkberry 'Gem Box' (2½ ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one clump. A single spire is too slight to hold a place alone, so here the accent is a clump.
Why now
- In flower for 17 weeks. From late June to mid October.
- Fills a gap. For one of those weeks nothing else on the plan is in flower.
- Stands through winter. Left uncut, it holds its shape until March, when the perennials have gone.
Planned as a naturalistic planting: low grasses and groundcovers, the matrix, make up 50% of the planted ground. Cool colours (pink, purple and blue) with red as the warm note, and white to calm things between them. Woodland strawberry repeats along the bed to tie it together.
The planner's own design check: 9 Excellent, 8 Good. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where purple fountain grass goes in a border
At 4 ft it belongs at the back of a bed. In the planner's ten height classes it is moderately tall (3 to 4 ft).
Its job: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
The most widely sold ornamental grass, grown as an annual in all but the warmest gardens. It is a sterile hybrid and sets no seed, unlike green fountain grass (Cenchrus setaceus), which is invasive in the Southwest and Hawaii.
- Summer containers
- A dark accent in seasonal bedding
- Warm-climate borders
What to plant with purple fountain grass
Plants recorded as good partners for it, and what each pairing does:
- Rosemary: flowers first, early March to early May, so the spot is never empty.
- Canna: purple against yellow, opposite each other on the colour wheel, if you choose those colours, in flower together for 14 weeks; bold leaves against its fine ones.
- Mexican bush sage: in flower together for seven weeks, from early September.
Choosing between it and a look-alike? Pink muhly grass vs Purple fountain grass.
Questions about purple fountain grass
Does purple fountain grass need sun or shade?
Purple fountain grass grows in full sun (6 or more hours of direct sun a day).
It wants ordinary well-drained soil, of average fertility, and a good soak in dry spells.
What zones does purple fountain grass grow in?
USDA zones 9 to 10. It is hardy to zone 9, which means it survives winter nights down to about 30 °F (−1 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
How far apart should purple fountain grass be planted?
24 in (60 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 2½ ft (75 cm), so a group knits into one patch.
It grows 4 ft (120 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many purple fountain grass plants do I need?
At 24 in apart, set out in staggered rows:
- 3 to fill 10 square feet (about 1 m²)
- 6 for a single row 10 ft (3 m) long
- 10 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as one at a time, repeated along the bed at intervals; a slender one reads better as a clump of three.
In the bed above, the planner used three in one group.
Is there a native plant like purple fountain grass?
Purple fountain grass is not native to North America. These North American natives come closest to doing its job:
- Switchgrass 'Shenandoah': the same job in a bed and the same size; grown for its leaves, not its flowers.
- Prairie blazing star: the same job in a bed; 8 in narrower, flowers mid July to late August.
- Carolina lupine: the same job in a bed and the same size; flowers late May to late June, yellow, not red.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What flowers after purple fountain grass?
Purple fountain grass is over by mid October. These start as it finishes and carry the same spot on, so it never goes flat:
- Bodnant viburnum 'Dawn': from early November to late December, 10 ft tall.
- Common witch hazel: from mid October to late November, 15 ft tall.
What does purple fountain grass look like in winter?
Purple fountain grass turns the colour of straw and, left uncut, stands through the winter. Cut it down in late winter, before the new shoots come up.
More Cenchrus
- Dwarf fountain grass 'Hameln' Cenchrus alopecuroides 'Hameln' (formerly Pennisetum)
- Fountain grass 'Burgundy Bunny' Cenchrus alopecuroides 'Burgundy Bunny'
- Fountain grass 'Little Bunny' Cenchrus alopecuroides 'Little Bunny'
- Oriental fountain grass 'Karley Rose' Cenchrus orientalis 'Karley Rose'
In these guides
- Tall perennials and grasses for the back of a border
- Long-flowering plants: 12 weeks or more
- Plants with purple and burgundy leaves
Zone guides: Zone 9
Every fact on record
- Type
- Grass
- Size
- 4 ft (120 cm) tall, 2½ ft (75 cm) wide
- Plant
- 24 in (60 cm) apart
- Height class
- Moderately tall (3 to 4 ft)
- Place in the bed
- Back
- Flowers
- Late June to mid October; feathery plumes; red, purple
- Leaves
- Fine texture, herbaceous; burgundy, purple
- Shape
- Arching, clumping
- Hardy in
- USDA zones 9 to 10
- Light
- Full sun
- Soil
- Average, well-drained
- Water
- Moderate
- Feeding
- Light, in spring
Not yet checked against an outside reference: its figures rest on general horticultural knowledge. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.