From their native, tropical habitat, plumerias have adapted well in many diverse climates throughout much of the world where admirers/worshipers have adopted and taken them. However, they have not adapted well to low temperature and excessive water.
Where I live in Huntington Beach, CA, low temperatures have not been a big problem. In the short 64 years I have been growing plumerias, I can count the number of plumerias I have lost to cold weather on one hand. So, I don’t worry much about low temperature.
My big problem is keeping the roots of my plumerias from having too much water during their dormant months. All of my plumerias planted in the ground are on a three- to six-inch mound that gives excellent drainage and prevents root rot. My problem is with my potted plants. With the soil level lower than the rim of the pot it can trap too much water and drown the root system. I move all movable potted plants under a roof and they get no water until I move them out in the spring. For bigger potted plants that would be difficult to move, I make a “coolie hat” out of tar paper and cover the pot so no rain can enter. Note: Be sure the planter mix in the pot is relatively dry before covering it.