Plumerias, also known as frangipani, are popular tropical plants celebrated for their highly fragrant and visually appealing flowers. They require specific temperature conditions to thrive and produce abundant blooms. Understanding these needs is crucial, as plumerias are sensitive to both extreme cold and excessive heat.
Optimal Temperature Range
For plumerias to exhibit active growth and prolific flowering, they thrive within a specific temperature range. Ideally, these plants perform best when temperatures remain between 65°F and 85°F (18°C-29°C) during their active growing season. Plumerias require at least six hours of direct sunlight daily within this optimal temperature window to encourage vibrant flowering.
Nighttime temperatures also influence plumeria health, with ideal lows consistently staying above 55°F (13°C). When nighttime temperatures consistently remain above this threshold, it signals the appropriate time to bring plumerias out of winter storage and encourage them to emerge from dormancy. Maintaining these temperatures supports overall plant vigor and sustained blooming.
Cold Hardiness and Winter Care
Plumerias are sensitive to cold, generally hardy down to about 33°F (0.5°C). Prolonged exposure to temperatures at or below 33°F can cause frost injury or plant death. Signs of cold stress include leaves turning brown or black, wilting, and stems becoming soft and mushy. If temperatures are expected to drop below 50°F (10°C), plumerias typically begin to lose their leaves and enter a dormant state, signaling the need for winter protection.
For container-grown plumerias in regions with cold winters, move them indoors when temperatures consistently fall below 50°F. During dormancy, plumerias do not require light and can be stored in a cool, dry place like a garage, closet, or basement, where temperatures remain above 35°F (1.7°C), preferably above 40°F (4.4°C). Watering should be significantly reduced or stopped entirely during this period; excess moisture can lead to root rot. If the stem appears shriveled, provide about half a cup of water per month.
For plumerias planted directly in the ground in cooler climates, protection is necessary when temperatures approach freezing.
Winter Protection Methods
Cover plants with frost cloth or blankets to trap ambient heat. Avoid plastic unless it does not touch the plant, as it transfers cold.
Wrap old-fashioned (non-LED) Christmas lights around branches for warmth.
Use pipe insulation around branches and trunks for added protection.
In areas where consistent freezing is a concern, dig up the plant and store it bare-root in a warm, protected space, ensuring roots do not contact cold concrete.
Heat Tolerance and Summer Management
Plumerias generally thrive in warm conditions, but excessive heat can still pose challenges. When temperatures consistently rise above 90-95°F (32-35°C), plumerias may experience heat stress. Signs of heat stress include leaf scorch, characterized by browning or burning of leaf edges, wilting, yellowing leaves, and premature flower drop. In extreme heat, plants may slow down or stop producing new leaves and flowers, and even drop existing leaves as a natural response to reduce water loss.
Summer Heat Management
Increase watering frequency, sometimes daily for potted plants, particularly during hot, dry periods. Water early in the morning to allow water to soak into the soil before high daytime temperatures cause rapid evaporation.
Deep water, reaching 12-18 inches into the soil, encourages the development of robust root systems that are more resilient to heat.
Provide afternoon shade, especially when temperatures exceed 100°F (37.8°C), to prevent leaf and bloom burn. Shade cloth can protect plants from intense midday sun and high UV ratings.
Ensure good air circulation to prevent fungal diseases that can arise from increased humidity with frequent watering. Proper spacing between plants and pruning to thin dense foliage can improve airflow.
Temporarily stop fertilizing during periods of extreme heat, as a sudden flush of nutrients can induce growth that requires more water, further stressing the plant.
Apply a 2-4 inch layer of organic mulch around the base of the plant to retain soil moisture and regulate soil temperature.