Bougainvillea performs well in a relatively small container where its roots are slightly restricted. When the plant is large enough for repotting, move it to a container only one size larger. Use a regular potting soil without a high level of peat moss; too much peat retains moisture and may result in root rot. Any container used for growing bougainvillea must have at least one drainage hole. Install a trellis or support at planting time; installing one later may damage the roots.
Water a newly planted bougainvillea frequently to keep the soil moist. Once the plant is established, it blooms best if the soil is a little on the dry side. Water the plant until liquid drips through the drainage hole, then don’t water again until the potting mixture feels slightly dry. However, don’t allow the soil to become completely dry because a water-stressed plant won’t bloom. Water the plant immediately if it looks wilted. Bougainvillea is a heavy feeder and requires regular fertilization to produce blooms throughout the growing season. You can use a water-soluble fertilizer mixed at half strength every seven to 14 days, or apply a slow-release fertilizer in spring and midsummer.
Bougainvillea blooms on new growth. This means you can prune the plant as needed to maintain the desired size. The ideal time to trim the plant is immediately following a flush of blooms.