(syn. Dipladenia)
These are woody stemmed, twining climbers from central and south America. As such they are all very firmly greenhouse plants in the UK which are frost tender so may well require a frost free (ie heated) environment over winter. That should not detract from the fact that these climbers have the most spectacular flowers in the summer and on into early autumn and are relatively easy to grow in a greenhouse with some trellis or other supports.
Loam based potting composts are best with shading from direct sunlight which can scorch the older leaves. Liquid fertiliser should be applied monthly in the summer growing season. When eventually dormant in the winter they can be pruned back into shape to encourage fresh new flowering shoots to develop in the following season. Do not be alarmed if these plants lose all their leaves in the winter but, with more heat, they will retain some or all of their leaves.
Mandevilla x amabilis ‘Alice du Pont’ has ovate and slightly wrinkled leaves. It is a vigorous climber with superb funnel shaped glowing pink flowers often in racemes and as singles. This plant can grow up to 15-20ft so pruning is essential and removing older dead leaves from time to time will help prevent any build up of whitefly or red spider mite infestations which need to be spotted and dealt with at an early stage.
Mandevilla laxa (M. suaveolens) is less vigorous in growth but just as impressive in flower. Its leaves are green above and grey-green on the undersides. The tubular flowers are pure white or creamy white in racemes of five or more flowers. The flowers are extremely fragrant. Of the three species described here this is the hardiest.
Mandevilla splendens (Dipladenia splendens) are even more tender than the others described here and definitely do need winter heat. M. splendens can present a variety of pink colour shades in its funnel shaped flowers which have white and yellow throats and also appear in small racemes. The leaves are broadly elliptic and very shiny. This is an evergreen plant which will usually not survive a total leaf loss from cold temperature.
All Mandevillas are best propagated from softwood new growth cuttings taken in early spring.
