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Bougainvillea does not follow the steady rhythm of most garden plants. It runs in bursts: a flush of growth, a period of stress, a flush of color, a hard cut, and round again. In a long warm season you can get two or three of these cycles; in a shorter one, a single good display. The calendar matters less than the stage the plant is at.
Everything is driven by two levers. The first is water, withheld on purpose to trigger bracts. The second is the cut, made once a flush of color has faded, which forces the new shoots that will carry the next display. Feeding is a minor adjustment on top of those two, and pest control is opportunistic.
The other fixed point is cold. Below about 41F (5C) the plant stops and sheds its leaves regardless of what you do, so the working year runs from the point night temperatures settle above 50F (10C) to the point they fall back through it.
Read the table below as a sequence rather than a set of dates. Whether your warm season is short or long, the order does not change.
| Season | What the plant does | What you do |
|---|---|---|
| Late winter | Dormant, bare stems | Prune the framework, keep dry |
| Early spring | Buds break on bare wood | Water a little more, first light feed, harden off |
| Late spring | Strong shoot extension | Tie in, start the dry cycle |
| Early summer | Growth stalls, bracts form at the tips | Stop feeding, keep it dry, full sun |
| Midsummer | Bracts open and hold | Water before drooping, no feed |
| Late summer | Bracts fade and go papery | Cut back hard, one feed, restart the dry cycle |
| Autumn | Second flush, then slowing | Reduce water, stop feeding |
| Early winter | Leaf drop, dormancy | Move under cover, water barely |
Spring: waking it up and building the framework
The season starts with the pruning cut, made in late winter before growth restarts. Because bracts form on new shoots, this cut is what determines how much color you get. Shorten the main stems by up to a third, take out anything dead, thin or crossing, and aim for a clear framework of four or five strong stems. Prune with thick leather gloves and long sleeves.
As buds break, increase watering slightly and give the first half-strength high-potassium feed. This is the only part of the year where a little generosity is right, because the plant needs to build the shoots that will carry the flowers. Even here, do not let the compost stay wet.
Tie in new growth while it is soft and flexible. Bougainvillea has no tendrils and does not attach itself, and a stem left to its own devices for a month becomes rigid and will snap rather than bend. Train stems roughly horizontal where you can, since shoots break more freely along a horizontal stem.
Do not repot unless you genuinely have to. If you must, do it now, move up one pot size only, and disturb the root ball as little as possible. The roots are brittle and a disturbed plant will often skip its first flush entirely.
Resist repotting a plant that is flowering well and looks crowded. Congested roots are one of the conditions producing that display, and a move into fresh, rich compost typically buys you a year of green growth and no color.
Summer: stress it, then hold the display
Once shoots have extended and the weather is warm, switch to the dry cycle. Soak the pot thoroughly, then wait until the youngest leaves droop, then wait a further day, then soak again. Stop feeding altogether while you do this. Four to six weeks of that treatment is usually enough to see bract clusters forming on tips that have stopped growing.
When the bracts are coloring, ease off slightly. Water a little sooner, before the drooping stage, so the display holds rather than being pushed further. A well-set flush lasts six to ten weeks because the color comes from bracts rather than petals, and bracts are modified leaves that persist.
Keep it in full sun throughout. Six hours minimum, eight or more if you can. Shade is the one problem that no amount of water management will solve, and a plant that has been dried hard and still refuses to color is nearly always in a position that is too dark.
Watch for the true flowers, the small cream tubes sitting in threes inside the bracts. When those have browned and dropped, the display is on its way out and the cut is coming.
| Stage of the flush | Watering | Feeding |
|---|---|---|
| Shoots extending | Moderate, dry between soaks | Half-strength high potassium every third watering |
| Forcing bracts | Dry until leaves droop, plus one day | None |
| Bracts coloring | Water at first sign of droop | None |
| Bracts open and held | Water before drooping | None |
| Bracts papery and pale | Normal, before the cut | One half-strength feed after cutting |
After the flush: cut it back and go again
This is the step that separates a plant which colors once from one that colors repeatedly. When a flush is spent, cut the flowered shoots back by about a third to a half, to just above a leaf joint on firm wood. Fresh shoots break from below the cut within a fortnight in warm weather, and those shoots carry the next display.
Give one half-strength feed straight after cutting to support the new growth, then stop again and restart the dry cycle as soon as the shoots are a few inches long. Timed well, this delivers a second flush six to eight weeks later.
Judge whether there is time. A cut made when there are two months of warm weather left will give you another display; the same cut made as nights start cooling produces soft growth that has no chance to harden and is the first thing lost to cold. If you are close to the end of the season, leave the plant alone and prune in late winter instead.
Bag the prunings rather than heaping them. The cut stems keep their thorns, they are invisible in a compost pile, and they go through shoe soles.
Autumn and winter: wind it down
As nights cool, stop feeding entirely and start reducing water. You want the growth on the plant to harden rather than stay soft, because soft tissue is what gets damaged first and what rots at the base in cold, damp conditions.
Bring container plants under cover before night temperatures approach 45F (7C), rather than waiting for a frost warning. Check for mealybug and spider mite before the pot goes into a still, sheltered space where they will thrive all winter. A bright, frost-free spot at 45 to 55F (7 to 13C) is ideal.
Expect leaf drop and do not treat it. A leafless bougainvillea with firm stems is dormant, not dying, and it needs almost no water in that state. Once every three or four weeks, and only when the compost is dry two inches (5 cm) down, is enough.
Then leave it until late winter, when the cycle starts again with the framework prune. The plants that fail over winter are, with very few exceptions, the ones that were watered on a summer schedule.
The log that makes next year easier
Because bougainvillea runs on stages rather than dates, a written record is worth more here than for most plants. What you want is not a calendar but a set of intervals you can reuse.
Record the date of each hard cut and the date color appeared afterwards. That interval, usually six to eight weeks, is what lets you aim a display at a particular point in the season next year. Record how many days it takes the pot to go from a full soak to drooping leaves, since that number is your entire watering schedule and it changes with pot size and position.
Note the date you moved the plant under cover, the date growth restarted, and the coldest temperature it actually saw. Note every feed, with type and strength, because a green and flowerless season almost always traces back to nitrogen you have forgotten giving. Two seasons of these notes and the plant stops being unpredictable.