Repotting guide

When & how to repot Bougainvillea 'San Diego Red' (Bougainvillea 'San Diego Red')

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.

Mature size: 6-9 m unrestrained; easily kept to 1.5-3 m by pruning or in pots

Watch for — Leaf and bract drop after a move: Bougainvilleas hate disturbance and cold draughts; keep them in a stable, warm, bright spot and avoid repotting in flower.

How to tell bougainvillea 'san diego red' needs repotting

Repotting on a calendar is less reliable than reading the plant. For bougainvillea 'san diego red', watch for these signs:

Thick roots out of the drainage holes, or circling the surface and lifting the plant.
The pot dries out unusually fast and bougainvillea 'san diego red' wilts between waterings it used to shrug off.
The plant is visibly top-heavy and tips over easily.
Stalled growth and small new leaves over a full season — though with a big specimen, top-dressing is often the better first response before a full repot.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot bougainvillea 'san diego red'

Every 2–3 years; top-dress in the in-between years. Bougainvillea 'San Diego Red''s 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. — sets the pace. 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.

What size pot to step bougainvillea 'san diego red' up to

Move up exactly one pot size. A heavy bougainvillea 'san diego red' dropped into a vastly bigger pot sits in a reservoir of wet soil its roots cannot reach, which rots them and destabilises the plant. In the years between repots, lift off and replace the top 3–5 cm of soil (top-dressing) instead — it refreshes nutrients without the shock of a full repot.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot bougainvillea 'san diego red'

Early spring, just as new growth restarts, is the ideal window for bougainvillea 'san diego red'. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting bougainvillea 'san diego red'

Consider top-dressing first. If bougainvillea 'san diego red' is not badly root-bound, scrape off and replace the top 3–5 cm of soil instead — far less shock for a big plant that hates moving.
Get help and one size up. For a full repot, choose a pot just one size larger. A heavy plant needs two people and a stable, free-draining pot.
Ease it out on its side. Lay the plant down, slide the pot off, and gently loosen the outer roots. Do not bare-root a mature specimen.
Repot at the same depth. Add fresh well-drained, low-fertility sandy loam beneath and around the rootball, keeping the original soil line. Firm it so the trunk is stable and upright.
Water and leave it put. Water thoroughly, then leave bougainvillea 'san diego red' in the same spot and light — moving and repotting at once is what makes it drop leaves.

Aftercare

Leave bougainvillea 'san diego red' in exactly the same spot and light it was in before — moving and repotting at the same time is what makes a big specimen drop leaves. Water it in well, then let the top of the soil dry before watering again so the larger volume of fresh soil does not stay sodden. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for bougainvillea 'san diego red'

Bougainvillea 'San Diego Red' wants well-drained, low-fertility sandy loam. Sharp-draining, slightly acidic soil (pH 5.5-6.5). Tolerates poor ground; rich, soggy soil reduces flowering and risks root rot. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting bougainvillea 'san diego red' — frequently asked questions

How often should you repot bougainvillea 'san diego red'?

Every 2–3 years; top-dress in the in-between years for bougainvillea 'san diego red'. Fully repot bougainvillea 'san diego red' only every 2–3 years; in the in-between years just top-dress the top 3–5 cm of soil. Step up one pot size in spring with well-drained, low-fertility sandy loam. It is heavy and hates being moved, and a vastly oversized pot holds water against the roots and rots them.

What size pot does bougainvillea 'san diego red' need?

When is the best time of year to repot bougainvillea 'san diego red'?

Should you top-dress or fully repot bougainvillea 'san diego red'?

For a big, heavy bougainvillea 'san diego red', top-dressing — replacing the top 3–5 cm of soil — is the gentler option most years, with a full repot only every 2–3 years. A mature specimen sulks and drops leaves when fully repotted, so do it as rarely as the roots allow.

Should you fertilise bougainvillea 'san diego red' after repotting?

Not immediately. Wait about 4 weeks after repotting bougainvillea 'san diego red'. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.