Bougainvillea trees are known for their vibrant, tissue-paper thin flowers that come in many shades, including red and yellow. Although these trees can grow up to 30 feet wide and 20 feet tall, they have thin root systems that require feeding on a regular basis. A constant supply of nutrients will ensure that your tree grows strong. Properly fertilized bougainvillea trees will bloom 11 months out of the year.
Water the soil beneath your bougainvillea tree before you apply fertilizer. Moist soil ensures that the tree absorbs the nutrients correctly.
Apply a water-soluble fertilizer with a nitrogen (N), phosphorous (P) and potassium (K) ratio of 2-1-2 to your tree during the summer months. Bougainvilleas require monthly feeding. Follow the instructions on the package to apply the correct amount.
Apply a slow or controlled-release fertilizer that is high in phosphate and has micronutrients containing iron in August and March. This type of fertilizer slowly releases the vitamins, but does not give the tree so much at one time that it only produces foliage.
Reduce the water-soluble fertilizer from step 2 by half and continue to feed your bougainvillea tree on a regular, monthly basis during the cooler months.