Why Is Your Bougainvillea All Leaves and No Flowers?

Bougainvillea is arguably the toughest flowering plant you can put on a Bengal rooftop. It bakes happily in 45 degree heat, shrugs off dust and pollution, and lives for decades in a pot. And yet the question we hear most at the nursery is always the same: why is mine all leaves and no flowers?

The answer is almost always too much kindness. Bougainvillea blooms hardest when life is a little hard. Water it generously, feed it richly, give it a roomy pot, and it will reward you with metres of lush green vine and not a single bract.

The three usual suspects

• Too much water. Constantly moist soil tells the plant that times are good, so it grows leaves instead of flowers.
• Too much nitrogen. Urea and high-nitrogen fertilizers produce vigorous green growth and completely suppress bract formation.
• Too little sun. Bougainvillea needs an absolute minimum of 6 hours of direct, unobstructed sunlight. Shade guarantees a flowerless plant.
• A pot that is too large. Restricted roots trigger blooming; a huge pot full of moist soil does the opposite.

The drought-stress technique

This is the single most reliable trick in the bougainvillea grower's book, and it is exactly how nurseries force those spectacular displays you see in winter.

• Stop watering completely until the leaves visibly wilt and droop.
• Then water deeply, until it drains from the bottom of the pot.
• Repeat this wilt-and-water cycle two or three times.
• The plant reads the stress as a survival signal and responds with a massive flush of colour.

Feed for flowers, not foliage

Swap general-purpose fertilizer for bloom food. Organic growers should use bone meal and wood ash. If you prefer chemical feeds, use a high phosphorus and potassium mix such as 0:52:34 at 1 gram per litre, applied after the drought cycle. Never apply plain urea.

One more thing: remove the water shoots

Those long, thorny green stems that rocket straight up are called water shoots. They rarely flower and they drain the plant's energy. Prune them off at the base and the plant will redirect that vigour into flowering branches.

Follow these rules and a healthy bougainvillea in full sun is practically guaranteed to bloom. It is not a delicate diva. It just wants to struggle a little.