Plumerias are tropical plants and sensitive to cold temperatures. Cold stress can become a concern for both small (1-gallon size) and larger (7’ to 8’, 15-gallon size) plumeria trees. Here are temperature guidelines to consider for the health of your plumerias:

Temperature Thresholds for Plumerias

1. Below 50°F (10°C): Begin to monitor closely. Plumerias can tolerate these temperatures for short periods, but prolonged exposure can lead to stress.
2. At or Below 40°F (4.4°C): Start getting worried. This temperature range can cause significant stress and damage, especially for prolonged periods. The risk is higher for smaller plants, as they have less resilience compared to larger, more established trees.
3. Freezing Temperatures (32°F or 0°C and below): Immediate action is needed. Plumerias are not frost-tolerant. Freezing temperatures can cause severe damage or even kill the plant, regardless of its size.

Protecting Plumerias from Cold

• Insulation: Use frost cloths, blankets, or burlap to cover your plants, especially overnight when temperatures drop.
• Location: If possible, move smaller potted plumerias indoors or to a warmer, protected area like a garage or greenhouse.
• Mulching: Apply a layer of mulch around the base of larger plants to help insulate the roots.
• Reduced Watering: Cut back on watering in cold weather, as plumerias enter a dormant state and require less water.
• Avoid Fertilizing: Stop fertilizing in the fall as this can encourage new growth that is more susceptible to cold damage.

Special Considerations

• Size and Maturity: Smaller, younger plumerias (like those in 1-gallon pots) are more vulnerable to cold than larger, mature trees. They have less established root systems and are less resilient.
• Microclimate: Microclimates in your garden can affect how plumerias experience cold. Areas sheltered from wind or near a south-facing wall may be warmer.
• Varietal Differences: Some plumeria varieties may have slightly different cold tolerances. It’s helpful to know the specific characteristics of your plants.

Conclusion

Regularly monitoring weather forecasts during the colder months is crucial for plumeria care. Being proactive in protecting your plants from cold stress is key, especially for smaller, less established plumerias. Remember, it’s better to err on the side of caution when it comes to cold temperatures and tropical plants like plumeria.