Fertilising guide
How to fertilise Bougainvillea (Bougainvillea glabra)— schedule & NPK
Also called Bougainvillea, Paper flower, Lesser bougainvillea.
More about bougainvillea
About Bougainvillea
Bougainvillea glabra · also called Bougainvillea, Paper flower · flowering
Bougainvillea glabra, or paper flower, is a thorny, sun-loving tropical climber prized for vivid papery bracts surrounding tiny true flowers. Give it full sun, fast-draining soil and lean watering to trigger blooms. Not listed by the ASPCA; the main risk is its large thorns, so verify safety with your vet.
Growth habit: Vigorous, woody, thorny evergreen climber (scrambling vine) grown for its bright papery bracts; the actual flowers are small and white. Responds well to hard pruning after flowering and is often trained on walls, trellises, or kept compact in containers.
Watch for — Few or no flowers: Usually too little sun, overwatering, or high-nitrogen feed driving leaves over bracts. Give full sun, let it dry between waterings, and switch to a low-nitrogen feed.
What fertiliser bougainvillea actually wants — and why
Bougainvillea flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.
Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency.
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 bougainvillea: 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 bougainvillea, 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 bougainvillea:
Feed monthly during active growth from spring to late summer. To maximise bracts, favour a low-nitrogen, higher-potassium/phosphorus formula once growth is established; excess nitrogen drives foliage at the expense of flowers. Stop feeding in autumn and winter. In practice: no routine feeding at all for bougainvillea — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.
The dormant-season rule matters more than the exact interval: skip feeding entirely when bougainvillea 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 bougainvillea
None is the correct answer for bougainvillea. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.
Feeding always goes onto already-damp soil, never dry roots — water bougainvillea first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the bougainvillea watering schedule.
Signs you are over-feeding bougainvillea
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for bougainvillea:
- Abundant leafy growth and very few flowers (the classic over-rich symptom).
- Soft, floppy stems and a sprawling, leafy habit.
- Scorched edges and salt crust if it has been fed in a container.
Signs you are under-feeding bougainvillea
- Effectively never an issue — these plants flower on poverty.
- Only on genuinely dead soil: weak, thin growth and few blooms.
- A short-lived plant in completely spent container compost.
If the symptoms point at watering, light or roots rather than nutrition, the full bougainvillea care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
If bougainvillea has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.
Organic vs synthetic feeds for bougainvillea
Organic options
A thin compost mulch for soil structure is the absolute most; mostly, give it nothing. UK/US: leave it lean — no manure, no liquid feed. Poor soil is the active ingredient here.
Synthetic / liquid feeds
None. Synthetic feeds, particularly anything with appreciable nitrogen, directly suppress flowering in bougainvillea.
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 bougainvillea — frequently asked questions
What fertiliser does bougainvillea need?
Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency. Bougainvillea flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.
How often should I feed bougainvillea?
Feed monthly during active growth from spring to late summer. To maximise bracts, favour a low-nitrogen, higher-potassium/phosphorus formula once growth is established; excess nitrogen drives foliage at the expense of flowers. Stop feeding in autumn and winter. Feed monthly during active growth from spring to late summer. To maximise bracts, favour a low-nitrogen, higher-potassium/phosphorus formula once growth is established; excess nitrogen drives foliage at the expense of flowers. Stop feeding in autumn and winter. In practice: no routine feeding at all for bougainvillea — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.
What strength of feed for bougainvillea?
None is the correct answer for bougainvillea. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.
What does over-feeding bougainvillea look like?
Abundant leafy growth and very few flowers (the classic over-rich symptom). Soft, floppy stems and a sprawling, leafy habit. Scorched edges and salt crust if it has been fed in a container. Feeding bougainvillea at all — especially "to help it flower" — is the defining mistake. Rich soil gives you a big green plant and almost no blooms; restraint is what produces the flowers.
Should I flush the soil of bougainvillea?
If bougainvillea has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.
Keep reading
- Bougainvillea care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water bougainvillea — 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