Also called frangipani, plumeria trees grown in tropical gardens for their fragrant, colorful blossoms, belong to the species Plumeria rubra. Plumerias lose their leaves in the dry winter months and bloom and leaf-out when heat and rains return in spring and summer. Do not allow frosts and freezes to reach plumeria trees, as it will cause rot and death to branches.
Whether grown outdoors in frost-free regions or in a heavy container, plumerias need a fast-draining soil. A sand-based soil with organic matter suffices in outdoor gardens, while a peat-based or coarse soil works well in containers. Generally, the soil does not need to be overly fertile.
The more sunlight a plumeria tree receives, the better. Provide this plant full sun year-round, where it receives at least eight hours of direct sun daily. In equatorial regions, where sun intensity and day length remains relatively strong and constant, light shade allows plumeria trees to still flower abundantly in summer.
Plumeria trees break their dormancy in spring, once the soil warms. When leaves and flowers emerge, heat promotes growth of roots and branch tips. The plant also tolerates increased watering when soil temperatures remain above 75 to 80 degrees F. In winter, the soil cools and aids in sending the plumeria into dormancy when it loses its leaves. Cooler soils need to remain dry to prevent root rot.
When branch tips begin revealing new growth and leaves in spring, water moderately with about 1 inch of rainfall or irrigation weekly. As temperatures in summer reach over 90 degrees F, additional water of up to 2 inches per week sustains growth well. By early autumn, reduce watering to no more than 1 inch per week, and once leaves naturally begin to yellow and drop away, lessen the watering more. A dormant, leafless plumeria needs a dry soil from late autumn to mid-spring, even if late flower clusters remain.
When fertilizing plumeria trees, use a fertilizer with a high phosphorous (P) content. This element helps to form larger and more abundant flowers. The nitrogen content (N) should be relatively low. Too much nitrogen enhances vegetative growth at the expense of flowers. Commercial products that meet the fertility needs for plumeria include Super Bloom and BR-61 formulas. Apply them to plumeria trees according to label directions, every other week, or at least once a month during the active growing season of mid-spring through late summer. Do not fertilize plants the rest of the year.