At this time of the year you'll find Dipladenia's on display in every market or garden centre. They are so flamboyant with shades ranging from white, pink to bright red. In its natural habitat in Central and South America you can even find yellow. There are more than 100 species. The Mandavilla/Dipladenia that has become so very popular lately is Dipladenia sanderii, originating in the highland above Rio de Janeiro. It is a climber, with lovely deep green glossy foliage, and from spring to autumn produces flowers continuously.
The first time I came across this plant was in Ireland. Some parts of Ireland are lucky enough to have a very mild climate. Visiting a garden there, I had my first sight of a white Mandavilla growing up a wall. Then, their official name was "Mandavilla". I saw them again being sold in florists in southern France, about 6 years ago. They were either white or pink in colour.
A few years ago another species was introduced, Dipladenia sanderii, it was just slightly different from the Mandavilla I had seen in Ireland. Their popularity increased with more shades becoming available each year. Their popular name changed from "Mandavilla" to "Dipladenia".
For us living in southern France it is good to know that their fleshy roots store water and the climber will survive a period without being watered, like being away on a two week holiday. It is frost tender, but in a frost free place it will survive from one year to the next.
After the winter, the branches need to cut back to 12 cm in length. It needs to be repotted in soil consisting of 2/3 garden compost and 1/3 sand. Make sure the base of the plant is well covered with soil.
Place the plant pot in a sunny position, but not a sun trap. Water regularly with soft water and feed the plant every 15 days. Remove the old flowers to encourage new flower buds to form.
Bibliography: Rustica and RHS A-Z Encyclopedia