Fertilising guide
How to fertilise San Diego Red Bougainvillea (Bougainvillea 'San Diego Red')— schedule & NPK
Also called San Diego Red Bougainvillea, Scarlett O'Hara Bougainvillea.
More about san diego red bougainvillea
About San Diego Red Bougainvillea
Bougainvillea 'San Diego Red' · also called San Diego Red Bougainvillea, Scarlett O'Hara Bougainvillea · tropical
A classic, vigorous bougainvillea cultivar bearing deep crimson-red bracts throughout the warm season, prized for its cold tolerance relative to other varieties. It grows quickly to 6–7 m with support and is highly drought-tolerant once established. Full sun and lean, well-draining soil are non-negotiable for its signature bold colour and heavy bloom load.
Growth habit: Vigorous woody scrambling vine with thorny arching canes
Watch for — Lack of flowering: Usually due to too much shade, overwatering, or high-nitrogen fertiliser. Position in full sun, reduce irrigation frequency, and apply a high-potassium, low-nitrogen feed to shift energy from leaf to bract production.
What fertiliser san diego red bougainvillea actually wants — and why
San Diego Red Bougainvillea is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
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 san diego red 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 san diego red 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 san diego red bougainvillea:
Apply a balanced fertiliser in early spring to support new growth, then switch to a low-nitrogen, high-potassium feed every 4–6 weeks during the blooming season. Excess nitrogen produces lush foliage at the expense of the spectacular bract display. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when san diego red 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 san diego red bougainvillea
Half strength is the safe default for san diego red bougainvillea — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water san diego red bougainvillea first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the san diego red bougainvillea watering schedule.
Signs you are over-feeding san diego red bougainvillea
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for san diego red bougainvillea:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding san diego red bougainvillea
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full san diego red bougainvillea care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of san diego red bougainvillea with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for san diego red bougainvillea
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
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 san diego red bougainvillea — frequently asked questions
What fertiliser does san diego red bougainvillea need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. San Diego Red Bougainvillea is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed san diego red bougainvillea?
Apply a balanced fertiliser in early spring to support new growth, then switch to a low-nitrogen, high-potassium feed every 4–6 weeks during the blooming season. Excess nitrogen produces lush foliage at the expense of the spectacular bract display. Apply a balanced fertiliser in early spring to support new growth, then switch to a low-nitrogen, high-potassium feed every 4–6 weeks during the blooming season. Excess nitrogen produces lush foliage at the expense of the spectacular bract display. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for san diego red bougainvillea?
Half strength is the safe default for san diego red bougainvillea — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding san diego red bougainvillea look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding san diego red bougainvillea year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of san diego red bougainvillea?
Flush the pot of san diego red bougainvillea with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- San Diego Red Bougainvillea care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water san diego red 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 anthurium andraeanum 'alabama'
- How to fertilise anthurium andraeanum 'acropolis'
- How to fertilise anthurium andraeanum 'baron'
- All 8452 fertilising guides in the Growli library