Bougainvillea and Loss of Leaves Even in Summer
Bougainvillea plants are delightful showpieces that boast small white flowers surrounded by brilliantly colored bracts. They require little care and small amounts of water. Sunshine is the most important requirement for these blooming beauties. Although low maintenance, they sometimes suffer heavy losses of leaves in the summertime. Many reasons exist for this, so it is best to examine your plants and their surroundings, and analyze the care and nutrients that they are receiving.
The most common reason for leaf loss in bougainvillea plants is over watering. These plants do not require large amounts of water, and care must be taken not to over do it when watering all of your plants in the same manner. They should be allowed to dry between watering and never be completely soaked. The opposite is also true; if plants are never watered, they can lose leaves.
You may be applying the correct amount of water to the plants but without proper drainage in the soil or pot, the water may stagnate, causing the bougainvillea to retain too much moisture. This results in leaf loss and possible root rot. Plant your foliage in soil that drains well -- add pine bark in pots and planters to assist the drainage. Choose containers with plenty of holes and drainage at the bottom. If planted in the ground, steer away from heavy clay or dense soils, which may not allow water to drain quickly and effectively.
If the amount of moisture is not the issue, it may be that the plant is infested with aphids. Examine the petals, leaves and stems carefully for signs of infestation. Insect sightings and movement may be indications that your plant's growth and health is in jeopardy. Aphids can be treated naturally by removing the tiny bugs by hand or by gently spraying the plant with water. They can also be treated with a mixture of vegetable oil, water and dish detergent.
Lack of Sunlight
Bougainvillea are some of the few plants that can handle drought and large amounts of sunlight. In fact, if these plants receive too much shade or are blocked from the sun, it may result in leaf drop. Plant your flowers in an area that will continue to receive full sun. Be aware that when other structures are added in the area they may reduce the amount of sunlight received, and the lessened light may negatively affect the brilliant flowers and cause the leaves to fall more heavily.
Change in Season
When the weather gets cooler and winter rolls around, leaf drop is only natural because of the reduced amounts of sunlight and lower temperatures. Plants will become dormant and need to be stored effectively. If in pots, move them to a warmer location such as a greenhouse, shed or garage where the temperature remains above 50 degrees F. Water about once a month during this time. In-ground roots can be left alone as they will survive cold winters due to the insulation provided by the soil surrounding them.