Q: I am finding two vines for sale in garden centers, neither of which I am familiar with, but both of which are very pretty. One is “dipladenia”, and the other is “allamanda”.
Information on each would indicate that it is a perennial, but nowhere does it speak to cold hardiness. Do you know anything about either one?
A: I know that both are perennial plants in the tropics but neither will survive a winter here.
Allamanda is a vining plant producing yellow, pink or red flowers.
Dipladenia is really Mandevilla sanderii. It has very little vining habit – it’s more like a spreading bush. It has pinkish flowers but it won’t cover your mailbox like a common mandevilla vine, Mandevilla splendens, or allamanda will.
If you decide to buy any of the three plants mentioned, you can overwinter them indoors by digging the plant before the first frost. Place it in a three gallon pot and cut it back to a foot tall. Place the pot in a spot that does not freeze, where some light can shine on the plant. A few leaves will appear along the stems but do not fertilize. Water only once per month. You can take the plant outdoors once again after mid-April.