A frost free greenhouse that stays cool all summer is perfect for this exotically perfumed climber. Indeed this is excellent run along high wires in a shady greenhouse or conservatory as this will seldom get too hot and there will be enough light next to the glass.
Mandevilla suaveolens is a tender deciduous climber from Argentina and Bolivia, and called the Chilean jasmine! Don’t you just love the way we give plants the wrong names? However the jasmine part is nearly right as this does have a similar heavy lily like scent that can fill the greenhouse especially in the evenings. The foliage is clean and decorative too.
This is not a difficult plant but if you wish it to perform well it makes by far the better display when planted in the greenhouse border and trained up trellis on a sunny wall- which should not get too hot. Then it will make three or four metres of growth festooned with flowers, in warmer climates it runs through trees much like honeysuckle.
But do not despair, grown in a large pot or small tub and trained up a tripod of canes you can still have many flushes of these pristine white petunia shaped flowers. These hang from the slender twining stems which have neat healthy green smooth leaves. A non-gardening friend said “looks pretty much like a bindweed to me”, which is not far wrong, though Mandevilla flowers have a yellow throat, and that gorgeous perfume.
As with so many greenhouse plants the compost or soil must be very well drained, mostly lime free, peat or peat substitute based and not over-rich. Add in some leaf-mould if you have any. And always use rainwater of course. Light foliar feeding with a potash rich solution will increase flowering and is most appreciated by plants in pots as these get older and larger, I use seaweed solution once a fortnight. The usual bother-some greenhouse pests may appear but Mandevillas are quite trouble free otherwise.
You can raise these from seed as they come fairly true and with luck will flower heavily from their second year. In winter the leaves drop and they just need keeping dryish and frost free till they burst again in spring.
I once saw a lovely specimen of this in Jamaica in the mountain town of Mandeville, a cool bright area, which obviously suited it superbly as it covered a large tree. The owner was so proud as he informed me the climber was named after the town! I thought it best not to tell him of his error, or that they were both named after different men, the town after an early governor, Lord Mandeville of Manchester, the climber after Mr Mandeville of Buenos Aires!
There are some other species that will interest the collector such as M. glabra, M. splendens and M. superba and a choice Splendens hybrid Alice duPont with rose pink to dark rose blooms, though this is a bit too vigorous for most greenhouses.