Mandevilla

The names often cause confusion: Dipladenia is the older botanical name that has stuck in the trade; the genus is correctly called Mandevilla today. Compact bushy varieties are usually sold as dipladenia, strongly climbing ones such as the Sundaville or Diamantina series as mandevilla — botanically it is the same family group.

Typical of the dogbane family, the plant carries white milky sap in all its parts. Gloves are worthwhile when pruning, as the sap can irritate skin — and it is the reason mandevilla should not stand within reach of nibbling pets.

Above all, mandevilla wants one thing from its position: warmth. Full-sun, even hot spots against a south wall are ideal; there it flowers tirelessly, while in cool shady corners it sets only a few buds. Night temperatures should stay above ten degrees, which is why we only move it out after the last late frosts in mid-May.

With watering, less is more. The thickened roots store water, whereas the plant quickly answers waterlogging with yellow leaves. The most common mistake is daily watering out of habit — better to let the soil dry somewhat in between and then water thoroughly.

Climbing varieties need a support early on, around which they twine themselves anticlockwise. Guide the shoots too late and you get a tangled ball that can hardly be unravelled. Pruning is possible at any time but costs flowers short-term, since the buds sit at the shoot tips.

Overwintering works in a bright spot at ten to fifteen degrees, say a conservatory or stairwell, with watering much reduced. Cut back hard in spring and re-accustom the plant slowly to sun from May — over the years seasonal plants grow into impressive container specimens.