How to grow trumpet vine
Overview
Trumpet vine (Campsis radicans) is a vigorous deciduous climber producing clusters of orange or red trumpet-shaped flowers in summer. It is grown to cover large structures like pergolas, fences, and walls, providing dense foliage and dramatic colour. Key to success is planting in full sun and providing a robust support, as mature vines become heavy and woody over time.
Varieties
- Campsis radicans 'Flava' — Produces soft yellow trumpet flowers, less common than the species but equally vigorous.
- Campsis radicans 'Atropurpurea' — Deep brick-red flowers; a compact selection good for smaller spaces.
- Campsis radicans 'Indian Summer' — Bred for abundant orange blooms over a long season; good heat tolerance.
Soil Preparation
Trumpet vine prefers a free-draining soil with a pH of 6.0–7.5. Before planting, work in well-rotted compost or aged manure to improve fertility. If drainage is poor, raise beds or add coarse sand and organic matter. Heavy clay soils benefit from gypsum and extra compost.
Growing Guide
Position trumpet vine in full sun with a strong, permanent support such as a pergola or trellis. Plant in well-drained soil; improve heavy clay with gypsum or organic matter. Space plants 1–2 m apart to allow spread. Dig a hole twice the width of the root ball and plant at the same depth as in the nursery pot. Water in well and mulch to conserve moisture. For cooler zones, plant after the last frost; in warmer regions, autumn planting is also suitable.
Sowing
Sow seeds in spring after scarifying or soaking in warm water overnight to improve germination. Plant seeds 1 cm deep in seed-raising mix, space 5 cm apart, and keep moist at 20–25°C. Germination takes 2–6 weeks. However, trumpet vine is more commonly propagated from hardwood cuttings or layering, as seed-grown plants may take longer to flower.
Care
Feed with a balanced slow-release fertiliser in early spring before new growth. Prune hard in late winter (July–August) to control size and encourage flowering on new wood. Remove dead, weak, or tangled stems, and train the strongest shoots onto the support. In tropical zones, additional pruning in autumn may be needed to manage rampant growth.
Companion Planting
Trumpet vine pairs well with other vigorous climbers like wisteria or jasmine, but avoid planting near smaller shrubs or trees it may smother. Good companions also include large native grasses or structural plants like yucca that won't be overpowered. Do not plant near house foundations or roof lines where the vine may cause damage.
Common Pests & Risks
Scale insects and aphids can infest new growth and stems; control with horticultural oil or insecticidal soap. Suckering (root suckers) can occur and should be cut off at ground level to prevent spread. In humid subtropical areas, powdery mildew may appear on leaves; improve airflow and apply a sulfur spray if needed. Watch for spider mites in hot, dry conditions.
Troubleshooting
Yellow leaves: often due to overwatering or poor drainage; allow soil to dry between waterings and improve drainage. Brown leaf edges: caused by salt buildup from fertiliser or water; flush soil thoroughly and use slow-release fertiliser. No flowers: usually from too much shade or over-fertilisation; ensure full sun and reduce nitrogen. Sparse foliage: may indicate scale infestation; treat with horticultural oil and prune affected stems. Suckers emerging far from the base: dig down and cut at the root origin; don't just mow them off.