Grow

Mandevillas

Among the prettiest of the summer-flowering vines are the South American mandevillas, many of which are known as dipladenias. They have some of the most beautiful flowers in the garden and they bloom prolifically during the warmer months.

1. Choosing a Mandevilla

Mandevillas fall into three loose groups:

Large-flowered mandevillas – These all have large flower trumpets that are set against deep green, occasionally pleated, leaves. There are many cultivars available.

Deciduous mandevilla (Mandevilla laxa) loses its leaves in winter, but makes up for this bare period by producing waves of fragrant summer flowers. This is the best mandevilla for colder districts. It’s said to tolerate down to -6 degrees and, even if cut back completely by the cold, it will re-shoot from the base. Mandevilla laxa’s perfume is particularly attractive at night.

Dipladenias – This is one of those curious cases where a plant’s common name ’dipladenia’is more complicated than its botanical name, but don’t let this put you off growing what are some of the best container plants. Dipladenias are considered to be forms of Mandevilla sanderii. Their smooth, shiny leaves start off with a light yellow-green colouration that gradually ages to deep green.

2. Caring for Mandevillas

All mandevillas need good drainage – overwatering causes many failures. The tuber- like roots, which are very efficient at holding water, are likely to rot if they remain wet for any length of time.

If soil is heavy and drainage is doubtful it’s safest to grow mandevillas in large pots. A 400mm or 500mm Yates Tuscan pot makes a good choice because these containers have plenty of drainage holes.

Use a quality potting mix (like Thrive Premium). Mulch with a light organic mulch (keeping it well clear of the trunk) and feed with Dynamic Lifter pellets or Thrive Once- A-Year Feeder. In colder areas potted mandevillas can be moved inside as winter approaches. They make good indoor plants if they’re placed near a well-lit window.

3. Pests and diseases

Watch out for aphids clustering on the new shoots in spring and summer. Pinch them off or squirt with Yates Bug Gun or Nature’s Way Insect Spray. The latter will also take care of the minute red spider mite that can infest the leaves when the plants are in dry situations. Scale insects can also be troublesome but these are easily wiped off with a cloth dampened with a little Conqueror Oil or, for more severe infestations, with an application of Confidor. Yates Rose Gun will take care of most insect pests, as well as the powdery mildew fungus that can attack the leaves.


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