Though tropical by nature, when protected from frost, plumerias are well suited to subtropical climates in the United States in states bordered by the Gulf of Mexico (mainly Florida and Texas), and in Southern California. Plumerias can also be grown indoors.
Plumerias can be grown in containers, in the ground, or containers sunk in the ground. During the months of active growth, ample sun, food, and water are essential. Healthy plumeria will grow vigorously and bloom regularly and profusely when they receive at least 6 hours of full sun per day and an ample amount of the proper fertilizers. Plumeria love lots of water, but can’t tolerate wet feet, so they must be planted in highly organic fast draining soil or in beds with adequate drainage. Clay, gumbo, and silt are examples of poor draining soils; avoid these at all costs.
The way you care for your plumeria depends on the season of the year. Bring your plants out of storage in the spring, watch them grow and bloom in the summer, prepare for dormancy and storage in the fall, and store them for the winter.
When the nighttime temperatures begin to usually remain above 50 degrees, plumeria can be brought out of winter storage and encouraged out of dormancy. Due to conditions of storage, some root loss and desiccation of branches is expected, this is no cause for alarm. This is the time to feed, water, top dress, and/or repot. Since the plant is dormant, it will be minimally disturbed by repotting and root pruning as necessary.
Repotting and root pruning are optional and are performed as with any other container grown plant. Top dress by scraping off the loose soil and dead roots from the first couple centimeters of soil. Replace the removed soil with a mixture of compost and/or well composed cow manure. Feed and water thoroughly using a fertilizer.
Place the plant in a warm and sunny location. Some people like to sink the container into the ground, but be sure it is in a raised and well drained area such as a rose bed. This promotes more vigorous growth, provides support, and prevents it from blowing over. Plumeria tips are fragile and easily snapped off when the plant blows over.
For plumerias, summer has arrived once a lush growth of leaves has developed. Many will bloom before developing leaves, others will not. Once the leaf growth has developed, the summer regimen of care can be followed.
As mentioned before plumeria are heavy feeders. However, in order to discourage excessive stem elongation and to promote flowering, fertilizers low in nitrogen and high in phosphorous are, once again, recommended. Keep a plumeria healthy by feeding once or twice a month, and watering as necessary. The recommended foods can be sprinkled directly on the soil and then watered in. Consider using two tablespoons per five gallon pot per month.
During exceptionally hot periods, plants in above ground containers may need thorough watering as often as every other day. Drooping leaves can indicate a thirsty plant. As with all plants, check the soil before watering, if its dry for the first several centimeters, water thoroughly. Certain varieties of plumeria find Texas heat excessive for nominal blossom production. If this appears to be a problem, move the plant into a “shifting shade” location for better flower production and keeping quality.
As the days begin to grow shorter during August and September, some lower leaf yellowing and drop is normal. Some varieties will attempt a fall bloom cycle, if you are lucky and the weather cooperates, plumeria can still be blooming into November and December! But watch out, an early frost can damage or kill the plant.
For plumeria, fall begins once the nighttime temperature frequently begins to drop below 55 degrees. Studies have concluded that plumeria stop growing when the average ambient temperature drops below 65 degrees. Stop feeding and reduce water to encourage the plant to go into its natural dormant period.
Some growers think that feeding after mid August may contribute to the black tip fungus problem, however this has not been proven. It is difficult to predict the weather and therefore it’s difficult to give a date by which your plumeria should be safely stored for the winter. By all means, if temperatures are expected to fall into the lower 30′s, the plants should be protected. Most varieties can be damaged or killed by temperatures in the low 30′s for even a few hours.
During the winter plumeria require very little care. In fact winter care could be considered winter storage. Before storage, the plumeria should be defoliated. The best way to do this is to cut each and every leaf off the plant at a point about 2 cm from the stem. If you don’t defoliate, the leaves will yellow and fall off during storage providing a good environment for pests and fungus (as well as make a mess).
Store the plumeria in a cool to warm, dry, and ventilated area such as a garage, storage shed, or your living room. Temperatures should not be allowed to fall below freezing in the storage area. During exceptionally cold periods, for example below 25 degrees outside, a small supplemental heater may be required for plants stored in unheated sheds. A cool greenhouse is not recommended for plumeria storage because it will tend to be too damp and thus promote black tip fungus and other fungus problems. Some people suggest not watering plumeria at all for the entire winter, but probably a small monthly drink does more good than harm, especially if the branches are getting desiccated and the plant is in a warm dry location. Since a defoliated plumeria takes up considerably less space than one in full leaf, they can frequently be stacked two and three high in the storage area.