Fertilising guide
How to fertilise Princess Flower (Tibouchina urvilleana)— schedule & NPK
Also called Princess flower, Glory bush, Purple glory tree, Lasiandra, Pleroma urvilleanum.
More about princess flower
About Princess Flower
Tibouchina urvilleana · also called Princess flower, Glory bush · flowering
Princess flower (Tibouchina urvilleana) is a tropical evergreen shrub prized for velvety leaves and royal-purple, five-petalled blooms. Give it full sun, consistently moist acidic soil, warmth, and frost protection. It is not individually listed by the ASPCA, so treat it as a possible mild irritant around pets and verify with your vet.
Growth habit: Fast-to-moderate, somewhat sprawling evergreen shrub or small tree with an erect, vase-shaped to rounded form; benefits from pinching and light pruning to stay bushy and tree-like.
Watch for — Yellowing leaves (chlorosis): Green-veined yellow leaves signal iron chlorosis from alkaline soil or water. Maintain acidic soil and feed with an acid-loving plant fertiliser.
What fertiliser princess flower actually wants — and why
Princess Flower is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves.
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 princess flower: 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 princess flower, 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 princess flower:
Feed every 2-4 weeks during spring and summer with a balanced or slightly acidic liquid fertiliser formulated for acid-loving plants; this supports its long bloom season. Reduce or stop feeding in autumn and winter when growth slows. Avoid over-fertilising, which pushes soft foliage at the expense of flowers. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
The dormant-season rule matters more than the exact interval: skip feeding entirely when princess flower 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 princess flower
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for princess flower. The variable that actually matters is pH, not concentration.
Feeding always goes onto already-damp soil, never dry roots — water princess flower first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the princess flower watering schedule.
Signs you are over-feeding princess flower
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for princess flower:
- Brown, scorched leaf margins from too strong or too frequent a dose.
- White salt crust on the soil surface.
- Soft, lush growth that fruits or flowers poorly.
Signs you are under-feeding princess flower
- Yellowing leaves with green veins (iron chlorosis from high pH).
- Weak growth, poor cropping and an overall pale, stressed look.
- Stunted new shoots in spring despite adequate water and light.
If the symptoms point at watering, light or roots rather than nutrition, the full princess flower care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush princess flower with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Organic vs synthetic feeds for princess flower
Organic options
Composted pine bark, pine-needle mulch, used coffee grounds and an organic ericaceous feed gently maintain acidity. UK: Vitax or Westland Ericaceous; US: Espoma Holly-tone or Dr. Earth Acid Lovers. Slow, soil-improving, hard to overdo.
Synthetic / liquid feeds
A liquid or granular ericaceous feed — UK: Miracle-Gro Ericaceous, Vitax or Westland; US: Miracle-Gro Acid-Loving Plant Food or Espoma Holly-tone. Pair with rainwater and an acidic mulch for it to work.
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 princess flower — frequently asked questions
What fertiliser does princess flower need?
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves. Princess Flower is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
How often should I feed princess flower?
Feed every 2-4 weeks during spring and summer with a balanced or slightly acidic liquid fertiliser formulated for acid-loving plants; this supports its long bloom season. Reduce or stop feeding in autumn and winter when growth slows. Avoid over-fertilising, which pushes soft foliage at the expense of flowers. Feed every 2-4 weeks during spring and summer with a balanced or slightly acidic liquid fertiliser formulated for acid-loving plants; this supports its long bloom season. Reduce or stop feeding in autumn and winter when growth slows. Avoid over-fertilising, which pushes soft foliage at the expense of flowers. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
What strength of feed for princess flower?
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for princess flower. The variable that actually matters is pH, not concentration.
What does over-feeding princess flower look like?
Brown, scorched leaf margins from too strong or too frequent a dose. White salt crust on the soil surface. Soft, lush growth that fruits or flowers poorly. Feeding princess flower an ordinary fertiliser, or growing it in hard tap water / limey soil, is the defining mistake — it triggers lime-induced chlorosis (yellow leaves, green veins) no amount of feeding fixes until the pH comes down.
Should I flush the soil of princess flower?
Flush princess flower with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Keep reading
- Princess Flower care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water princess flower — 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 peace lily
- How to fertilise bird of paradise
- How to fertilise hoya
- All 609 fertilising guides in the Growli library