Purple Fountain Grass (red fountain grass) care

Light

Purple Fountain Grass needs sun on the leaves, not just bright ambient room light. Full sun is essential; the deep purple colour and free flowering both depend on at least six hours of direct light. In shade the foliage greens out and growth thins. A south or west-facing windowsill in the northern hemisphere is the default; anywhere else, expect the plant to stretch and pale out within a season.

Watering

Water purple fountain grass when the top 2-3 cm of soil dries, roughly weekly in the ground and more often in containers. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. Keep evenly moist while actively growing, especially in pots, which dry fast. Established plants tolerate short dry spells but flower and colour best with regular water.

Soil and pot

Purple Fountain Grass grows best in fertile, well-drained soil or quality potting mix. Grows in most well-drained soils and thrives in rich container compost. Sharp drainage is important, as cool wet soil quickly rots this heat-loving grass. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Purple Fountain Grass sits happiest at around Any outdoor humidity humidity and 10 to 35°C (50 to 95°F). A warm-climate grass tolerant of humidity and indifferent to it; the limiting factor is cold, not moisture in the air. If you keep the room above 10 to 35°C year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed purple fountain grass sparingly. Feed lightly but regularly when grown in containers, every few weeks through summer with a balanced liquid feed, since potting mix is quickly depleted. In-ground plants need only a light spring feed. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on purple fountain grass in the Growli community. Each is annotated with the most common cause so you know where to start.

• Frost death — Even a light frost kills the top growth and the plant rarely survives cold winters; lift and overwinter indoors or treat as an annual.
• Green, dull foliage — Insufficient sun fades the purple colour and reduces flowering; move to the brightest possible spot.
• Container dry-out — Pot-grown plants wilt fast in heat; check moisture daily in summer and water before the mix fully dries.
• Crown rot — Cold, soggy soil rots this heat-loving grass; ensure excellent drainage and avoid overwatering in cool weather.

Propagation

Propagate by division of the crown in spring; the cultivar 'Rubrum' is sterile and does not set viable seed, so division is the only reliable method. Keep divisions warm and bright to re-establish. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Purple Fountain Grass is mildly toxic to pets. Pennisetum setaceum is not individually listed in the ASPCA toxic plant database, and the sterile cultivar 'Rubrum' is widely regarded as non-toxic; because there is no direct ASPCA listing, treat its safety as uncertain and confirm with a vet. The clearer hazard is mechanical — bristly, sharp-awned plumes and blades can irritate or lodge in pets, and eating grass can cause mild GI upset. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Purple Fountain Grass deep-dive guides

Every aspect of purple fountain grass care, each with its own calibrated guide:

• Purple Fountain Grass watering schedule
• Purple Fountain Grass light requirements
• Best soil mix for purple fountain grass
• Purple Fountain Grass fertilizing guide
• When to repot purple fountain grass
• How to propagate purple fountain grass
• Purple Fountain Grass growth rate & size
• Purple Fountain Grass cold hardiness
• Purple Fountain Grass temperature & humidity
• Is purple fountain grass toxic to cats & dogs?
• Is purple fountain grass toxic to cats?
• Is purple fountain grass toxic to dogs?
• Getting purple fountain grass to bloom

Featured in these plant shortlists

Purple Fountain Grass qualifies for 3 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best flowering houseplants — Indoor plants grown for their blooms — selected from the flowering species in Growli’s plant-care library.
• Best houseplants for full sun — Houseplants that want direct sun — the species for a hot south or west-facing windowsill where shade-lovers scorch.
• Best houseplants for a cool room — Houseplants that tolerate cool conditions down to about 10°C — for an unheated spare room, hallway, porch or a home kept cool.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Purple Fountain Grass is also commonly called purple fountain grass or red fountain grass.

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