Bougainvillea & Acid Soil

Ideal Soils

• Bougainvilleas thrive in slightly acidic soils with a pH of just over 6, according to Clemson University extension floriculture specialist Al Pertuit. The pH scale runs from 0 to 14, with 7 being neutral. The Bougainvillea Growers International nursery also states that the vines grow best in acidic soil with a pH of between 5.5 and 6.5. Bougainvilleas will grow in gardens with a wide range of soil types with pH values ranging from slightly acidic to slightly alkali.

Nutrients and pH

• Bougainvillea vines grown in soil with a pH of more than 6 are more vulnerable to deficiencies in micronutrients such as iron, according to Kent D. Kobayashi from the University of Guam's Department of Tropical Plant and Soil Sciences. Fertilize bougainvilleas with a low nitrogen fertilizer enriched with iron to encourage healthy growth and plenty of flowers.

Soil Type

• Bougainvillea vines have a fine root system and are very vulnerable to root rot. Avoid planting container-grown bougainvilleas in peat-based compost as it is highly water retentive while being slightly acidic. Use a soil-less, peat-free mix with added perlite or pine bark to increase drainage, or an equal mix of sand, silt, and clay. Keep container-grown bougainvilleas slightly pot bound to increase the number of flowers. Never allow the soil to dry out completely and water your plant at the first sign of wilting.

Diagnosing Problems

• Bougainvillea vines with plenty of leaves but only a few flowers need more direct sunshine or higher temperatures, or may be receiving too much nitrogen. Move to a brighter, warmer spot and use a low nitrogen feed. Leaf spots and yellow foliage are signs that your vine is being overwatered. Reduce watering and check the drainage holes at the bottom of the containers.