Purple Fountain Grass
Pennisetum setaceum Rubrum
Dramatic ornamental grass with burgundy foliage and feathery purple plumes.
Grown as a warm-season accent in Phoenix Zone 9b-10a; it thrives in intense summer heat but foliage burns and dies back below about 25°F, often returning from the crown after mild winters.
AMWUA Notes
Note: Pennisetum setaceum (green form) is considered potentially invasive per ADWR. Use sterile "Rubrum" cultivar only.
Care Guide
Water established clumps every 10-14 days in summer and monthly in cooler months. It tolerates low water but looks fullest with regular deep irrigation during peak heat.
Cut back to a few inches above the crown in late winter before new growth begins to remove tattered, frost-damaged foliage. Comb out old blades any time to keep clumps neat.
Apply a light application of balanced fertilizer in spring as growth resumes; it is not a heavy feeder and needs little else through the season.
Largely pest- and disease-free. In overly wet or shaded conditions watch for occasional rust or crown rot from poor drainage.
Foliage colors deepest and plumes appear from summer into fall. Expect winter dieback with frost; shear old growth in late winter and it flushes back with warm weather.
Soil, Feeding & Propagation
Adaptable to most well-drained soils; performs well in average garden, sandy, or amended desert soils.
Needs well-drained soil.
Low feeder.
The Rubrum cultivar is sterile and does not come true from seed; propagate only by division of established clumps in spring.
3-4 ft
Fibrous, clumping, non-invasive roots; the sterile Rubrum cultivar will not reseed like the invasive species form.
Placement Tips
- •Mass in groups of three or five to amplify the movement of the burgundy foliage and plumes in the breeze.
- •Plant along borders, in containers, or at a pool edge where afternoon backlighting sets the plumes glowing.
- •Give each clump 3-4 feet of space so the fountain-like form arches freely without crowding.
- •Pair the dark foliage against light gravel, pale walls, or golden-flowered plants for high contrast.
Features
Best Uses
Companion Plants
Quick Stats
Design Styles
Include in Your Project
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Use this care guide to maintain your Purple Fountain Grass. Questions about your landscape? Reach out anytime.
Data from 2024 AMWUA “Landscape Plants for the Arizona Desert” guide.
Purple Fountain Grass — common questions
Answers for low-desert Phoenix conditions, drawn from this plant’s growing data.
How much water does Purple Fountain Grass need in Phoenix?
Purple Fountain Grass is a low-water ornamental grass once established. Water established clumps every 10-14 days in summer and monthly in cooler months. It tolerates low water but looks fullest with regular deep irrigation during peak heat. Note: Pennisetum setaceum (green form) is considered potentially invasive per ADWR. Use sterile "Rubrum" cultivar only.
How big does Purple Fountain Grass get?
Expect roughly 3-5 ft tall and 3-4 ft wide at maturity, with a fast growth rate. Allow about 3-4 ft of spacing when planting. Fibrous, clumping, non-invasive roots; the sterile Rubrum cultivar will not reseed like the invasive species form.
Can you plant Purple Fountain Grass near a pool?
Yes. Purple Fountain Grass is considered pool-friendly, meaning it stays clean enough around water features and hardscape. Litter is rated low.
Can Purple Fountain Grass handle Arizona heat and winter frost?
Purple Fountain Grass is hardy in USDA 9-11 and wants full sun. Grown as a warm-season accent in Phoenix Zone 9b-10a; it thrives in intense summer heat but foliage burns and dies back below about 25°F, often returning from the crown after mild winters. Foliage colors deepest and plumes appear from summer into fall. Expect winter dieback with frost; shear old growth in late winter and it flushes back with warm weather.
Does Purple Fountain Grass have thorns?
No. Purple Fountain Grass is thornless, so it is safe alongside walkways, patios and play areas.
Is Purple Fountain Grass safe around pets?
Purple Fountain Grass is listed as pet-friendly in this guide. If your dog is a determined chewer, check any new plant with your vet before planting.
When does Purple Fountain Grass bloom in Arizona?
Purple Fountain Grass blooms in summer-fall, with purple flowers.
How much maintenance does Purple Fountain Grass need?
Purple Fountain Grass is moderate-maintenance. Leaf, flower and pod litter is rated low. Cut back to a few inches above the crown in late winter before new growth begins to remove tattered, frost-damaged foliage. Comb out old blades any time to keep clumps neat.
What kind of soil does Purple Fountain Grass need?
Adaptable to most well-drained soils; performs well in average garden, sandy, or amended desert soils. Nutrient needs are low. Apply a light application of balanced fertilizer in spring as growth resumes; it is not a heavy feeder and needs little else through the season.
Is Purple Fountain Grass native to Arizona?
No. Purple Fountain Grass is not an Arizona native; it originates from the Africa, Middle East, but it is grown successfully in low-desert landscapes here.