Fertilising guide
How to fertilise Rose Grass (Rhodohypoxis baurii)— schedule & NPK
Also called Rose Grass, Red Star.
More about rose grass
About Rose Grass
Rhodohypoxis baurii · also called Rose Grass, Red Star · flowering
Rhodohypoxis baurii is a compact South African alpine bulb producing a long succession of star-shaped pink, red, or white flowers from late spring through summer. It thrives in gritty, perfectly drained soil and demands a dry winter dormancy. Ideal for rock gardens, troughs, or alpine house cultivation in cooler climates.
Growth habit: Compact, clump-forming perennial bulb (rhizomatous corm) with grass-like foliage and stemless flowers arising from the crown.
What fertiliser rose grass actually wants — and why
Rose Grass is a heavy-blooming flower with a big appetite — a regular high-potash feed through the season is what drives a long, dense display.
A high-potassium ("high-potash") flowering feed — tomato-style or a dedicated bloom/rose feed. Potassium powers flowering; a high-nitrogen feed gives you a leafy plant with disappointing bloom.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for rose grass: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed rose grass, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For rose grass:
Apply a balanced, low-nitrogen liquid fertiliser (e.g., 10-10-10) at half strength every 3–4 weeks during the growing season (spring–summer). Stop feeding once flowering ends and the plant begins to die back for dormancy. For a hungry bloomer that means feeding regularly — sparingly through the growing season — right through flowering across the main season (spring through early autumn), tapering as blooming ends.
The dormant-season rule matters more than the exact interval: skip feeding entirely when rose grass is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for rose grass
Follow the flowering-feed label rate for rose grass, or half strength if feeding very frequently. These plants genuinely use the nutrients — under-feeding shows up fast as a thin display.
Feeding always goes onto already-damp soil, never dry roots — water rose grass first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the rose grass watering schedule.
Signs you are over-feeding rose grass
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for rose grass:
- Lots of lush leaves but few flowers (too much nitrogen).
- Scorched leaf edges and salt crust from too-strong or too-frequent feeds.
- Soft, sappy growth prone to aphids and mildew.
Signs you are under-feeding rose grass
- Sparse, small, short-lived flowers and pale foliage.
- A tired plant that stops blooming early in the season.
- Weak growth and poor repeat-flowering after the first flush.
If the symptoms point at watering, light or roots rather than nutrition, the full rose grass care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Container-grown rose grass accumulates feed salts fast with frequent feeding — water until it drains each time and flush pots with plain water every few weeks to prevent scorch.
Organic vs synthetic feeds for rose grass
Organic options
A liquid comfrey or seaweed feed (naturally potassium-rich) plus compost or well-rotted manure as a mulch. UK: comfrey feed, organic Tomorite, or rose feed; US: Espoma Rose-tone or Neptune's Harvest. Feeds and improves soil.
Synthetic / liquid feeds
A high-potash flowering feed on a regular cadence — UK: Tomorite (Levington), Phostrogen or a specialist rose feed; US: Miracle-Gro Bloom Booster or a rose food. Fast, reliable bloom response.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising rose grass — frequently asked questions
What fertiliser does rose grass need?
A high-potassium ("high-potash") flowering feed — tomato-style or a dedicated bloom/rose feed. Potassium powers flowering; a high-nitrogen feed gives you a leafy plant with disappointing bloom. Rose Grass is a heavy-blooming flower with a big appetite — a regular high-potash feed through the season is what drives a long, dense display.
How often should I feed rose grass?
Apply a balanced, low-nitrogen liquid fertiliser (e.g., 10-10-10) at half strength every 3–4 weeks during the growing season (spring–summer). Stop feeding once flowering ends and the plant begins to die back for dormancy. Apply a balanced, low-nitrogen liquid fertiliser (e.g., 10-10-10) at half strength every 3–4 weeks during the growing season (spring–summer). Stop feeding once flowering ends and the plant begins to die back for dormancy. For a hungry bloomer that means feeding regularly — sparingly through the growing season — right through flowering across the main season (spring through early autumn), tapering as blooming ends.
What strength of feed for rose grass?
Follow the flowering-feed label rate for rose grass, or half strength if feeding very frequently. These plants genuinely use the nutrients — under-feeding shows up fast as a thin display.
What does over-feeding rose grass look like?
Lots of lush leaves but few flowers (too much nitrogen). Scorched leaf edges and salt crust from too-strong or too-frequent feeds. Soft, sappy growth prone to aphids and mildew. Using a high-nitrogen general feed on rose grass is the headline mistake — you grow a big leafy plant with few flowers. The second is simply under-feeding a genuinely hungry bloomer and getting a sparse, short display.
Should I flush the soil of rose grass?
Container-grown rose grass accumulates feed salts fast with frequent feeding — water until it drains each time and flush pots with plain water every few weeks to prevent scorch.
Keep reading
- Rose Grass care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water rose grass — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise variegated purple moor grass
- How to fertilise tall moor grass
- How to fertilise skyracer moor grass
- All 8452 fertilising guides in the Growli library