Feeding Bougainvillea: The Low-Nitrogen Rulebook

If you remember one thing about feeding bougainvillea, remember this: nitrogen grows leaves, phosphorus and potassium grow flowers. Most disappointing, flowerless plants we see at the nursery have been lovingly overfed with exactly the wrong thing.

The organic schedule

• February and September: work 50 g vermicompost, 20 g bone meal and 10 g neem cake into the top soil of a 30 cm pot.
• Late November: a generous dose of bone meal (30 g) plus wood ash (20 g) to fuel the winter bloom.
• Liquid feeds like mustard cake water: only sparingly, at most once every two months, well diluted.

The chemical alternative

• Use bloom-focused formulas: 13:0:45 (potassium nitrate) or 0:52:34 (mono potassium phosphate) at 1 g per litre, every 20 days through the growing season.
• The most reliable bloom trigger we know: a drought-stress cycle followed by one dose of 0:52:34.
• Never apply plain urea or high-nitrogen lawn fertilizer. The plant becomes a giant green shrub with zero flowers.

Reading the leaves: micronutrients

• Older leaves yellowing between green veins: magnesium deficiency, very common here. Spray Epsom salt at 2 g per litre monthly.
• Newest leaves yellow with green veins: iron deficiency, typical in alkaline mixes. Spray chelated iron (Fe-EDTA) at 0.5 g per litre.
• Browning leaf tips and margins: potassium hunger. Wood ash or a potash feed fixes it.
• Reddish purple tint on old leaves and poor blooming: phosphorus shortage. Bone meal is the classic cure.

Underfeed rather than overfeed, keep the nitrogen minimal, and let the sun and a little thirst do the rest. That is the whole rulebook.