Shrub · Nyctaginaceae
Bougainvillea
Bougainvillea spectabilis
Keep it sunny, thirsty, and a little neglected, and bougainvillea answers with a riot of color.
Full sun
Every 7–14 days
USDA 9–11
15–40 ft · 4.6–12.2 m
Overview
Bougainvillea is the plant behind those walls of color you see draped over fences and archways in warm climates. It's a woody, thorny shrub from South America that can climb or sprawl to 15 to 40 feet (4.6 to 12.2 m) when it's happy, or stay neat and small in a pot. What looks like a flower is really a cloud of papery bracts, which is how it picked up the name paper flower.
The catch with bougainvillea is that it blooms best when it's a little stressed. Pamper it with rich soil, steady water, and heavy feeding and you get a lush green plant with hardly any color. Hold back instead, give it blazing sun and lean, dry conditions, and the bracts pour out from spring into fall.
It is hardy outdoors only in USDA zones 9 to 11, where a hard frost is rare. Gardeners in colder places grow it in a container and move it under cover for winter, since it grows fast and takes pruning well. The one constant is the thorns, so heavy gloves are part of the job.
Care
The short version: all-day sun, soil that drains fast, and water only when the top has dried out. Feed lightly, go easy on the nitrogen, prune after it flowers, and protect it from frost.
Light
Bougainvillea wants full sun, at least 6 hours a day, and the more the better. Shade is the quickest way to a green plant with no color, since it needs strong light to set bracts at all.
Water
Water deeply, then let the top of the soil dry out before the next drink, usually every 7 to 14 days once the plant is established. It is drought tolerant and actually blooms better kept on the dry side, while constant moisture brings leaves instead of bracts and risks root rot.
Soil
Plant it in well-drained sandy or loamy soil. It likes the pH slightly acidic to neutral, in the range of 6.0 to 7.0, and won't tolerate ground that stays soggy.
Temperature
It thrives in heat and handles anything from about 30°F to 100°F (-1°C to 38°C). Frost is the line it won't cross, so anywhere below freezing means cover or a move indoors.
Humidity
Average humidity suits it fine, and there's no target number to hit. It is far more particular about sun and dryness at the roots than about moisture in the air.
Feeding
Feed monthly from spring through midsummer with a balanced fertilizer at half the usual rate. Keep the nitrogen low, because a heavy feed pushes leafy growth at the expense of the bracts you're after.
Pruning
Prune in late winter or early spring after flowering, and save any major cutting back for once the bloom period ends. Always wear heavy gloves, since the thorns bite.
Repotting
Repot every 2 to 3 years or when it outgrows the container. A snug, slightly pot-bound root ball actually encourages flowering, so there's no rush to size up.
Size & spacing
Given room, it reaches 15 to 40 feet (4.6 to 12.2 m) tall with a spread to match, so give a climbing plant a sturdy wall or trellis. In a pot it stays far smaller, and the dwarf cultivars are made for tight spots.
When to plant
Bougainvillea runs on warmth and won't take a frost. Set plants out in spring once the cold has truly passed, and they bloom from spring through fall, sometimes carrying color into winter where the weather stays mild.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: after all danger of frost has passed in spring
- Harvest: spring through fall, sometimes into winter
Hardiness
USDA hardiness zones: 9–11
Temperature: down to -7°C
Troubleshooting
Most bougainvillea trouble shows up as either no color or dropped leaves, and both trace back to its growing conditions more than to disease. Read the signs below, match them to what your plant is doing, and adjust before a small slip turns into a bare, sulking shrub.
Leaves and bracts dropping all at once
A sudden shed almost always follows a shock, usually a cold snap, a draft, or being moved to a new spot. Frozen leaves and shoots look water-soaked and then blacken. Keep the plant in one stable, warm, sunny place, water it on an even keel, and bring containers indoors before the temperature drops near 30°F (-1°C).
Fix:
- Protect from frost and bring containers indoors before temperatures fall below about 30 degrees F
- Keep the plant in a stable location and avoid moving it
- Maintain consistent watering, avoiding both drought and waterlogging
Yellow leaves with green veins still showing
When new leaves turn yellow but the veins stay green, the plant can't pull up enough micronutrients, usually because the soil is too alkaline or stays wet too long. Keep it in slightly acidic, well-drained ground and let the soil dry between waterings. A foliar micronutrient spray made for citrus or palms greens the leaves back up.
Fix:
- Maintain slightly acidic, well-drained soil
- Apply a foliar micronutrient spray suitable for citrus or palms
- Improve drainage and avoid keeping soil constantly wet
Lots of green leaves but barely any color
A leafy plant with no bracts almost always means it is too comfortable. Bougainvillea blooms when it is stressed, so cut back on water, move it into at least 6 hours of full sun, and ease off the nitrogen. A little drought and even a slightly pot-bound root ball push it to flower.
Fix:
- Move to or provide full sun (6 or more hours direct)
- Allow soil to dry out between deep waterings and reduce watering
- Stop high-nitrogen feeding; use a balanced fertilizer at a reduced rate
- Allow the plant to become slightly pot-bound or stressed to encourage blooming
Scalloped, chewed leaf edges with dark droppings
This is the bougainvillea looper, an inchworm-like caterpillar that feeds after dark and notches the leaf margins. Check the plant at night to catch them in the act, then pick them off by hand. For a heavier infestation, treat young larvae with Bt or reach for spinosad, which knocks down both young and mature caterpillars.
Fix:
- Handpick caterpillars, checking at night when they feed
- Apply Bacillus thuringiensis (Bt) to control young larvae
- Apply spinosad, which controls both young and mature larvae
Toxicity
Good news for pet and animal owners: bougainvillea carries no known toxin, so a chewed leaf won't poison a cat, dog, or grazing animal. The real hazard is physical. Stiff, sharp thorns line the stems and can cause puncture wounds, scratches, and sometimes dermatitis, and the sap may sting sensitive skin, so wear heavy gloves when you handle it.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
No toxic compound here, so a curious cat won't be poisoned by a nibble. The real risk is the stiff thorns, which can scratch a paw or face, so keep a potted plant out of a leaping cat's path.
Dogs None
Bougainvillea is safe for dogs to be around, and chewing a leaf won't poison them. A dog brushing through the canopy can catch a thorn, though, so watch for the odd scratch or puncture rather than any sickness.
Horses Safe
Nothing in the plant harms a horse if grazed. The sharp spines are the only concern, since a horse pushing into the branches can pick up a puncture wound.
Rabbits Safe
A rabbit can eat bougainvillea leaves without any poisoning. Keep the thorny stems away from a small animal, where a spine could do real damage to soft skin or an eye.
Livestock Safe
Cattle, goats, and sheep face no toxic threat from this plant. The woody thorns are what to mind, as they can scratch hide or muzzle when animals browse through the growth.
Birds Safe
Birds nest and perch in bougainvillea without harm, and there is no toxin to worry about. The dense, spiny branches actually give small birds good cover.
People Safe
The plant won't poison anyone, but the thorns will. Their punctures and scratches can lead to dermatitis or, rarely, a skin infection, and the milky sap may sting sensitive skin, so wear heavy gloves whenever you prune or handle it.
Not chemically poisonous, but the plant has sharp woody thorns/spines that cause puncture wounds and scratches (rarely skin infection or dermatitis), and the sap may cause mild skin irritation in sensitive people. The physical thorns are the real hazard, not chemical poisoning. Wear heavy gloves when pruning or handling.
Varieties
Bougainvillea comes in a wide spread of colors and sizes, from big climbers to dwarf forms made for pots. These are the ones you'll run into most.
Barbara Karst
A vigorous grower that throws out vivid red to magenta bracts in heavy flushes.
San Diego Red
A popular large red cultivar prized for how heavily it blooms.
Raspberry Ice
A compact pick with variegated foliage set against rose-red bracts.
California Gold
Stands out for its warm yellow to gold bracts instead of the usual pinks and reds.
Pixie
A dwarf, naturally compact form that fits well in a container.
Helen Johnson
A dwarf, compact cultivar that does well in pots and hanging baskets.
How to propagate
Bougainvillea is straightforward to multiply if you have patience, and the best results come from copying a plant you already grow rather than starting from seed.
Stem cuttingsModerate
Summer · Several weeks to a few months
The usual way to make more plants is from cuttings taken in summer. Cut a piece of current-season growth, set it in a sand and peat mix, and give it patience, since roots take anywhere from a few weeks to a few months to form.
LayeringModerate
Growing season · Several weeks to months
You can also layer it during the growing season by pinning a low stem down to root while it stays attached to the parent. It takes several weeks to months before the new section has enough roots to cut free.
SeedDemanding
Warm season · Slow and variable
Growing from seed is possible in the warm season but slow and unpredictable, and seedlings rarely match the parent. That's why named cultivars are almost always grown from cuttings or layers instead.
Myths
The colorful parts of a bougainvillea are its flowers.
Those bright papery petals are actually modified leaves called bracts, not flowers at all. The real flowers are the tiny white or cream tubes tucked in the center of each cluster, easy to miss against all that color.