How to grow mandevilla
Overview
Mandevilla sanderi is a tropical climbing vine from the Apocynaceae family, grown for its showy, trumpet-shaped flowers and glossy foliage. It softens vertical structures like trellises, fences, and pergolas, adding lushness and height to gardens. In Australia, it thrives in warm, frost-free climates and needs support to climb.
Soil Preparation
Mandevilla prefers slightly acidic to neutral soil (pH 6.0–7.0) with excellent drainage. Amend heavy clay with coarse sand and compost to prevent root rot. In pots, use a premium, free-draining potting mix with added perlite. Ensure the site does not stay waterlogged after rain.
Growing Guide
Plant Mandevilla in a spot with bright, indirect light and protection from harsh afternoon sun, especially in subtropical zones. Use well-draining soil enriched with organic matter; space plants 60–90 cm apart for trellis coverage. Set the root ball at the same depth as the nursery pot, and water deeply after planting to settle. Train tendrils onto supports early, as they twine naturally; avoid letting stems sprawl on the ground. In tropical areas, plant in the cooler dry season to reduce transplant shock.
Care
Feed monthly from spring through autumn with a balanced liquid fertiliser (e.g., 10-10-10) to support flowering. Prune after each bloom cycle to shape and remove spent stems; cut back to a healthy node. In late winter, trim lightly to renew growth and remove weak or crossing branches. Train new tendrils onto supports as they develop to maintain structure.
Companion Planting
Pair Mandevilla with other warm-climate climbers like Bougainvillea or Jasmine for a layered trellis display. Underplant with low-growing, shade-tolerant plants such as Liriope or Dianella to fill the base. Avoid planting near aggressive root systems like Bamboo, which compete for moisture.
Common Pests & Risks
Aphids and whitefly can cluster on new growth and leaf undersides, causing sticky honeydew and sooty mould. Scale insects appear as brown bumps on stems and leaves, weakening the plant. Control with a horticultural oil spray or neem oil applied fortnightly; for heavy infestations, use systemic insecticide. Check regularly in humid weather, when pests thrive.
Troubleshooting
Yellow leaves: overwatering or poor drainage—check soil moisture and reduce watering. Brown leaf edges: low humidity or salt burn from hard water—mist leaves or use filtered water. Leggy growth: insufficient light—move to a brighter spot. Bud drop: sudden temperature change or dry air—maintain consistent warmth and humidity. No flowers: too much nitrogen—switch to a bloom-boosting fertiliser with higher phosphorus.