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Fertilising guide

How to fertilise Bougainvillea 'San Diego Red' (Bougainvillea 'San Diego Red')— schedule & NPK

Also called San Diego Red Bougainvillea.

More about bougainvillea 'san diego red'

About Bougainvillea 'San Diego Red'

Bougainvillea 'San Diego Red' · also called San Diego Red Bougainvillea · flowering

Bougainvillea 'San Diego Red' (also sold as 'Scarlett O'Hara') is a large, vigorous cultivar bearing deep true-red bracts and dark green leaves. One of the most cold-tolerant and sun-loving bougainvilleas, it flowers heavily on lean, dry, well-drained soil in full sun. Thorny and fast-growing, it makes a bold wall, fence, or pillar climber in warm regions.

Growth habit: Vigorous, thorny, woody evergreen climber with long arching canes; needs tying to a support and hard pruning to control size and stimulate flushes of bracts.

Watch for — Poor bract colour: Too much shade, water, or nitrogen; relocate to full sun, dry it out between waterings, and use a bloom-focused feed.

What fertiliser bougainvillea 'san diego red' actually wants — and why

Bougainvillea 'San Diego Red' 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 bougainvillea 'san diego red': 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 'san diego red', 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 'san diego red':

Apply a high-potassium, low-nitrogen bloom fertiliser every 3-4 weeks during active growth; excess nitrogen gives leaves at the cost of bracts. Stop feeding over winter. Treat that as every 3-4 weeks 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 bougainvillea 'san diego red' 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 'san diego red'

Half strength is the safe default for bougainvillea 'san diego red' — 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 bougainvillea 'san diego red' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the bougainvillea 'san diego red' watering schedule.

Signs you are over-feeding bougainvillea 'san diego red'

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for bougainvillea 'san diego red':

Signs you are under-feeding bougainvillea 'san diego red'

If the symptoms point at watering, light or roots rather than nutrition, the full bougainvillea 'san diego red' care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Flush the pot of bougainvillea 'san diego red' 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 bougainvillea 'san diego red'

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 bougainvillea 'san diego red' — frequently asked questions

What fertiliser does bougainvillea 'san diego red' 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. Bougainvillea 'San Diego Red' 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 bougainvillea 'san diego red'?

Apply a high-potassium, low-nitrogen bloom fertiliser every 3-4 weeks during active growth; excess nitrogen gives leaves at the cost of bracts. Stop feeding over winter. Apply a high-potassium, low-nitrogen bloom fertiliser every 3-4 weeks during active growth; excess nitrogen gives leaves at the cost of bracts. Stop feeding over winter. Treat that as every 3-4 weeks 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 bougainvillea 'san diego red'?

Half strength is the safe default for bougainvillea 'san diego red' — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

What does over-feeding bougainvillea 'san diego red' 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 bougainvillea 'san diego red' 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 bougainvillea 'san diego red'?

Flush the pot of bougainvillea 'san diego red' 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.

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