Well I do know Plumeria very well my wife keeps them going every year and we live in a cold climate of Southeastern PA. They need to be planted you should have one shoot from another plant. With no roots put it in a planted 8”pot with some good potting soil. Give it some water if your in a warm climate 70 degrees or more put it outside. They don’t like cold under 65 and definitely no frost. Since we have winter here already plants are inside and staying dormant over the winter. The leaves fall off but then in early summer back outside they go and everything will grow back. Give it some tropical plant food and should bloom for you by next year. After the plant has been established for a couple years it will start forming another shoot. These can be cut off right at the branch out. Stick it in a pot and you will have another plant growing!
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