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Plant care

Palmarosa (Rosha Grass) care

Cymbopogon martinii

Also called Rosha Grass, Turkish Geranium Grass, Indian Geranium.

RHS H2USDA 9-11Pet-safeIndoor 100-180 cm tall

Watering rhythm

5-10days

When the top 3-5 cm of soil is dry, roughly every 5-10 days depending on temperature

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Light

Direct sun (at least 4-6 hours)

Soil

Light, free-draining sandy loam

Humidity

40-70%

Temp

15-35°C

Pet safety

Pet-safe

Mature size

100-180 cm tall

Care at a glance

Light

Aim for at least 4-6 hours of direct sun on the leaves. Requires at least 6-8 hours of direct sun daily. In shade it produces fewer aromatic oils and becomes prone to disease. If your only bright window faces south, that's perfect for palmarosa — same window any aroid would fry on.

Watering

Watering palmarosa: when the top 3-5 cm of soil is dry, roughly every 5-10 days depending on temperature. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Drought-tolerant once established. Reduce watering significantly in winter. Waterlogged roots lead to rapid decline.

Soil and pot

Palmarosa grows best in light, free-draining sandy loam. Tolerates poor, infertile soils. Good drainage is essential — avoid heavy clay. pH 6.0-7.5 is ideal. 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

Palmarosa sits happiest at around 40-70% humidity and 15-35°C (59-95°F). Native to tropical/subtropical climates and tolerates high humidity. Adequate air circulation reduces fungal issues at the base. If you keep the room above 15 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 palmarosa sparingly. Apply a balanced slow-release fertiliser (e.g. 10-10-10) at the start of the growing season. A light liquid feed monthly through summer supports leaf oil production without excessive leafy growth. 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 palmarosa in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Root rot in waterlogged soil — Ensure pots and beds have excellent drainage. Never let roots sit in standing water.
  • Rust fungus — Orange pustules on leaves in humid conditions. Improve airflow and remove infected blades promptly.
  • Mealybugs — White woolly clusters at leaf bases, especially on container plants. Treat with neem oil or insecticidal soap.
  • Die-back in cold winters — Not frost-hardy. Lift and overwinter in a frost-free greenhouse in USDA zones below 9.
  • Clump overcrowding — Older clumps become woody and less productive. Divide every 2-3 years in spring to rejuvenate.

Companion plants

Palmarosa pairs well with Lemongrass, Vetiver, Lavender, and Rosemary. These are species with similar light and water needs, so you can grow them in the same bed or container without conflict.

Propagation

Divide established clumps in spring, ensuring each division has several healthy shoots and roots. Can also be raised from seed sown indoors at 20-25°C, though germination is slow and seedlings should be potted on before transplanting out. 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

Palmarosa is pet-safe. Cymbopogon martinii is not listed as toxic by the ASPCA. As with most ornamental grasses, occasional nibbling by pets is unlikely to cause more than mild gastrointestinal irritation from grass fibre. 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.

Palmarosa care — frequently asked questions

What is the common name for Cymbopogon martinii?

Cymbopogon martinii is most commonly called Palmarosa, but it is also known as Rosha Grass, Turkish Geranium Grass, Indian Geranium. The names refer to the same species, so care instructions for Palmarosa apply identically to anything sold as Rosha Grass.

How much light does palmarosa need?

Palmarosa grows best in direct sun (at least 4-6 hours). Requires at least 6-8 hours of direct sun daily. In shade it produces fewer aromatic oils and becomes prone to disease.

How often should I water palmarosa?

Water palmarosa when the top 3-5 cm of soil is dry, roughly every 5-10 days depending on temperature. Drought-tolerant once established. Reduce watering significantly in winter. Waterlogged roots lead to rapid decline. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is palmarosa toxic to cats and dogs?

Palmarosa is pet-safe. Cymbopogon martinii is not listed as toxic by the ASPCA. As with most ornamental grasses, occasional nibbling by pets is unlikely to cause more than mild gastrointestinal irritation from grass fibre.

What USDA hardiness zone does palmarosa grow in?

Palmarosa is rated for USDA zone 9-11 and RHS hardiness H2. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Palmarosa deep-dive guides

Every aspect of palmarosa care, each with its own calibrated guide:

Featured in these plant shortlists

Palmarosa qualifies for 2 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Palmarosa is also known as Rosha Grass, Turkish Geranium Grass, and Indian Geranium.