Shrub · Nyctaginaceae
Bougainvillea
Bougainvillea spectabilis
Give it sun, a touch of thirst, and a little benign neglect, and bougainvillea rewards you with color.
Full sun
Every 7–14 days
USDA 9–11
15–40 ft · 4.6–12.2 m
Overview
Those tumbling walls of color you spot over fences and archways in warm places are very often bougainvillea. It is a woody, thorny shrub from South America, and when it is settled and content it can climb or sprawl to 15 to 40 feet (4.6 to 12.2 m), yet it stays tidy and small in a pot if that suits you better. The part that reads as a flower is really a soft mass of papery bracts, and that papery look is exactly where the name paper flower comes from.
The quirk worth knowing, and the one that trips up new growers, is that bougainvillea flowers best when life is a little hard. Treat it to rich soil, generous watering, and heavy feeding and you tend to get a leafy green plant with very little color to show for it. Ease off instead, hand it scorching sun and lean, dry conditions, and the bracts come pouring out from spring into fall. If yours is all leaves right now, that is completely fixable.
Outdoors it is only truly hardy in USDA zones 9 to 11, where a hard frost rarely visits. If you garden somewhere colder, do not be discouraged: keep it in a container and bring it under cover for winter, since it grows fast and is forgiving of pruning. The one steady fact is the thorns, so count heavy gloves as part of the routine and you will be fine.
Care
The short version: plenty of sun all day, fast-draining soil, and a drink only once the top has dried out. Feed it gently, keep the nitrogen modest, prune once it has flowered, and shield it from frost. You really cannot get this far wrong.
Light
Bougainvillea is happiest in full sun, at least 6 hours a day, and honestly the more it gets the better it does. Too much shade is the surest route to a green plant with no color, since it needs strong light before it will set bracts at all.
Water
Give it a deep drink, then let the top of the soil dry out before the next one, which usually works out to every 7 to 14 days once it has settled in. It copes well with drought and actually colors up better when kept on the dry side, while soil that stays wet gives you leaves rather than bracts and can invite root rot, so erring toward dry is the safe habit.
Soil
Settle it into well-drained sandy or loamy soil and it will thank you. It prefers the pH slightly acidic to neutral, somewhere in the range of 6.0 to 7.0, and it really does not like ground that stays soggy underfoot.
Temperature
Heat suits it beautifully, and it takes anything from about 30°F to 100°F (-1°C to 38°C) in its stride. Frost is the one line it will not cross, so once temperatures dip toward freezing, cover it or move it indoors and you have nothing to worry about.
Humidity
Average humidity is perfectly fine, and there is no particular number you need to chase. It cares far more about getting its sun and staying dry at the roots than it does about the moisture in your air.
Feeding
Feed it monthly from spring through midsummer using a balanced fertilizer at half the usual rate. Go light on the nitrogen, because a rich feed pushes leafy growth and holds back the very bracts you are hoping to see.
Pruning
Do your pruning in late winter or early spring after flowering, and hold any big cutting back until the bloom period has wrapped up. Slip on heavy gloves first, because those thorns do bite, and the plant takes a trim in good humor.
Repotting
Move it up a pot every 2 to 3 years or whenever it has clearly outgrown the one it is in. A snug, slightly pot-bound root ball actually nudges it to flower, so there is no need to rush it into something bigger.
Size & spacing
Given the room, it climbs to 15 to 40 feet (4.6 to 12.2 m) tall with a spread to match, so a climber will want a solid wall or trellis to lean on. Kept in a pot it stays far more modest, and the dwarf cultivars are tailor-made for snug corners.
When to plant
This is a warmth-loving plant that simply will not sit through frost, so there is no pressure to rush. Wait until spring has settled and the cold is genuinely behind you, then enjoy color from spring through fall, and sometimes into winter where the weather stays kind.
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
Almost every wobble with bougainvillea comes down to one of two things: not enough color, or a sudden leaf drop. Both are usually about its surroundings rather than disease, which is good news, because that means they are easy to put right. Look at what your plant is showing you, find the closest match below, and make a small change. A sulking shrub almost always perks back up.
Leaves and bracts let go all at once
A sudden shed nearly always comes right after a shock, most often a cold snap, a draft, or a move to a new spot. Frozen leaves and shoots take on a water-soaked look and then turn black. Settle it in one steady, warm, sunny place, water it on an even rhythm, and bring containers indoors before the temperature drops near 30°F (-1°C), and it will recover.
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 the veins still green
When fresh leaves go yellow while the veins stay green, the plant is struggling to take up enough micronutrients, usually because the soil is too alkaline or stays wet for too long. Keep it in slightly acidic, well-drained ground and let the soil dry between waterings. A foliar micronutrient spray meant for citrus or palms will green the leaves back up nicely.
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
Plenty of green leaves but hardly any color
A leafy plant with no bracts nearly always means it is having too easy a time. Bougainvillea colors up when it is stressed, so dial back the water, give it at least 6 hours of full sun, and ease off the nitrogen. A spell of drought, and even a slightly pot-bound root ball, will coax it into flower, and none of this does any lasting harm.
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
Chewed, scalloped leaf edges with dark droppings
What you are seeing is the bougainvillea looper, an inchworm-style caterpillar that munches after dark and notches the leaf margins. Step out at night and you can catch them at work, then simply pick them off by hand. If the numbers are higher, treat the young larvae with Bt, or turn to spinosad, which sees off both young and grown 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
Here is something to put your mind at ease: bougainvillea has no known toxin, so a curious nibble will not poison a cat, a dog, or a grazing animal. The thing to actually watch is physical. Stiff, sharp thorns run along the stems and can give puncture wounds, scratches, and occasionally dermatitis, and the sap may sting sensitive skin, so slip on heavy gloves before you handle it.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
There is no toxic compound at play, so a curious cat that takes a nibble will not be poisoned. The genuine risk is the stiff thorns, which can scratch a paw or a face, so keep a potted plant clear of where a leaping cat tends to land.
Dogs None
Bougainvillea is fine for dogs to be around, and a chewed leaf will not poison them. A dog pushing through the canopy can snag a thorn, though, so keep an eye out for the odd scratch or puncture rather than any illness.
Horses Safe
Grazing does a horse no harm, as there is nothing toxic in the plant. The sharp spines are the only thing to mind, since a horse leaning into the branches can pick up a puncture wound.
Rabbits Safe
A rabbit can eat bougainvillea leaves with no poisoning at all. Just keep the thorny stems away from a small animal, where a single spine could really hurt soft skin or an eye.
Livestock Safe
Cattle, goats, and sheep face no toxic threat from this plant. The woody thorns are the part to watch, as they can scratch hide or muzzle when animals browse their way through the growth.
Birds Safe
Birds perch and nest in bougainvillea without coming to harm, and there is no toxin to give a second thought. The dense, spiny branches actually offer small birds welcome cover.
People Safe
The plant will not poison anyone, but the thorns are a different story. Their punctures and scratches can bring on dermatitis or, in rare cases, a skin infection, and the milky sap may sting sensitive skin, so reach for 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 turns up in a lovely range of colors and sizes, from sprawling climbers to little dwarf forms happy in a pot. Here are the ones you are most likely to meet, and any of them is a kind choice for a beginner.
Barbara Karst
A strong grower that puts out vivid red to magenta bracts in heavy flushes.
San Diego Red
A well-loved large red cultivar valued for just how freely it blooms.
Raspberry Ice
A compact choice with variegated foliage paired against rose-red bracts.
California Gold
Notable for warm yellow to gold bracts rather than the familiar pinks and reds.
Pixie
A dwarf, naturally tidy form that settles happily into a container.
Helen Johnson
A dwarf, compact cultivar that takes well to pots and hanging baskets.
How to propagate
Making more bougainvillea is easier than you might expect, as long as you bring a little patience. The kindest path is to copy a plant you already have rather than starting from seed.
Stem cuttingsModerate
Summer · Several weeks to a few months
The most common route to new plants is from cuttings taken in summer. Snip a length of current-season growth, tuck it into a sand and peat mix, and let it be, since roots can take anywhere from a few weeks to a few months to appear. Patience is the only real skill needed.
LayeringModerate
Growing season · Several weeks to months
Another gentle option is layering during the growing season: pin a low stem down so it roots while still joined to the parent. Give it several weeks to months before the new section has rooted enough to cut away on its own.
SeedDemanding
Warm season · Slow and variable
Starting from seed is possible in the warm season, but it is slow, unpredictable, and the seedlings seldom resemble the parent. That is exactly why named cultivars are nearly always raised from cuttings or layers instead.
Myths
The colorful parts of a bougainvillea are the flowers.
Those bright papery petals are really modified leaves called bracts, and not flowers at all. The true flowers are the small white or cream tubes nestling in the middle of each cluster, and they are easy to overlook against so much color.