Plant problems

Why Are My Campsis Leaves Curling?

Q: Why are my campsis leaves curling?

Campsis (trumpet vine or trumpet creeper) leaves curl most commonly in the UK because of aphid infestation on the young shoot tips, cold damage in hard winters or from late spring frosts, drought stress in the first one to two years after planting, or waterlogging. Campsis is a genus of vigorous, woody, self-clinging deciduous climbers from North America (Campsis radicans, trumpet creeper) and East Asia (Campsis grandiflora, Chinese trumpet vine); the hybrid Campsis x tagliabuana (of which 'Madame Galen' is the most widely grown UK cultivar) combines the hardiness of Campsis radicans with the larger flowers of Campsis grandiflora and is generally the best choice for UK gardens. All produce clusters of large, tubular, trumpet-shaped flowers in shades of orange, red, and yellow from July to September; the flowers are attractive to hummingbirds in their native range and to bees and hoverflies in the UK. Campsis is a warm-climate plant that needs a long, hot summer to flower well, which means that in UK conditions a south or south-west facing wall in full sun is essentially mandatory for good flowering performance; the plant grows well enough in the UK but flowers poorly or not at all without sufficient summer warmth. Aphids are the most common cause of leaf curl in UK campsis: the pinnate leaves and young shoot tips are colonised by greenfly in spring and summer, causing leaflet curl and tip distortion. Cold damage is most visible in late winter on plants in exposed positions that have not had the protection of a warm wall.

Q: Why is my campsis not flowering?

Campsis fails to flower in UK gardens most commonly because it is not receiving enough heat and sunlight, because it is too young (the plant typically takes three to five years after planting to flower), or because it has been pruned at the wrong time. In the UK, campsis is right at the limit of its climatic range for reliable flowering; it needs the sustained warmth of a south or south-west facing wall in full sun to ripen the wood sufficiently for flower bud initiation in late summer, and in cool, cloudy UK summers the wood may not ripen adequately. On north-facing walls, in shaded positions, or in cooler, northern UK gardens, campsis may grow vigorously for many years without ever flowering. Pruning timing is critical: campsis flowers on the current year's growth produced from the permanent framework; all new shoots should be left unpruned until flowering is over in September, and then pruned back to two to three buds from the main framework in late winter (February to March). Pruning the new growth in spring or early summer removes the developing flower buds and prevents flowering entirely. Excessive nitrogen feeding encourages vigorous leafy growth at the expense of flowers; feed with a high-potassium fertiliser (tomato feed) from June onwards to encourage flower bud formation over leaf production. A young plant will not flower until it has established a sufficient root system and woody framework; patience for three to five years after planting is essential. If the plant has been growing for more than five years in a genuinely hot, sunny position, has had no nitrogen fertiliser, and has been pruned only in late winter, and still does not flower, the position may be simply too cool or too shaded for reliable UK campsis flowering.

Q: Is campsis hardy in the UK?

Campsis radicans (North American trumpet creeper) is the hardiest species and is fully hardy throughout most of the UK, surviving to at least -20°C when established; it was grown successfully in the UK as a wall plant for well over a century and rarely suffers serious winter damage on a sheltered wall in any but the most severely cold UK winter. Campsis grandiflora (Chinese trumpet vine) is less hardy (surviving to about -10 to -15°C) and is best restricted to the warmest, most sheltered UK positions. Campsis x tagliabuana 'Madame Galen', the most widely grown UK cultivar, is hardy to about -15°C and is considered reliably perennial in most of the UK on a south or west-facing wall; it may have shoot tips damaged in very hard winters (below -15°C) but typically regrows from the main woody framework in spring. All campsis species are deciduous and drop their leaves in October to November, at which point they are at their most cold-resistant; cold damage to the overwintered stems is rarely a problem for established plants of hardy campsis on a sheltered wall in the UK. The main winter risk is to young, newly planted specimens in their first winter before they have established a substantial woody root system; protect newly planted campsis with a fleece wrapping in November and mulch the roots with composted bark to insulate the crown.

Q: How do I prune campsis in the UK?

Campsis is pruned in late winter (February to March) to maintain a permanent framework of main stems on the wall and to encourage the maximum production of flowering side shoots in the current season. The pruning method is similar to that used for wisteria in late winter: cut all the long side shoots produced the previous season back to two to four buds from the permanent main stems; the stumps of these pruned side shoots develop into a system of fruiting spurs over the years. Do not prune in spring or summer as this removes developing flower buds and reduces the season's flowering. In the first two to three years, train the main stems out horizontally along wires fixed to the wall to build up the permanent framework; tie in shoots as they extend in summer. Once the main framework is established, the late-winter pruning controls the plant and maintains flowering. If a campsis plant has become very large and unmanageable over many years without adequate pruning, it can be cut back hard to the main stems (even to within 1 m of the ground) in February to March; it will regenerate vigorously from dormant buds on the old wood and produce a fresh framework, though hard-pruned plants will not flower until they have rebuilt sufficient new wood (usually two to three seasons after hard renovation). In the UK, the hard winter pruning is particularly important: the plant needs to be kept under firm control, as unpruned campsis spreads aggressively by suckering and by the aerial roots that adhere to walls.

Campsis (trumpet vine) is a vigorous, woody, self-clinging deciduous climber with large, tubular, orange or red trumpet flowers in July to September; one of the most spectacular flowering climbers for a warm UK wall. The hybrid Campsis x tagliabuana 'Madame Galen' is the most reliable cultivar in UK conditions. Aphids on the pinnate leaves and cold damage are the most common causes of leaf curl; the most frequently asked question about campsis in the UK is why it does not flower despite growing vigorously.

Aphids

Aphids are the most common cause of leaf curl on campsis in UK gardens; the pinnate leaves with their multiple paired leaflets are colonised by colonies of greenfly in spring and summer, causing the leaflets to curl inward and the young shoot tips to distort. The infestations are typically heaviest in May and June during the main growth flush and tend to decline as natural predators (ladybirds, lacewings, hoverfly larvae) arrive and the plant grows away from the damage. Heavy aphid pressure produces honeydew that attracts sooty mould on the leaf surfaces below the infested shoots.

What to do

No treatment is usually needed; natural predators control light infestations within a few weeks and the vigorous growth of campsis on a warm wall quickly outgrows the damage. Pinch off the most heavily colonised shoot tips to remove large colonies quickly. Apply insecticidal soap spray to young growth if the infestation is very heavy; the spray must contact the aphids directly. Avoid high-nitrogen feeding that produces the very soft, lush growth most attractive to aphids; feed with a potassium-rich fertiliser (tomato feed) from June onwards to encourage flowering rather than soft leafy growth.

Cold damage

Cold damage on campsis is most visible in late winter and early spring: on young or recently planted specimens, or on plants in exposed positions, hard frost below -10 to -15°C (depending on species and cultivar) can damage or kill the shoot tips and smaller stems, causing them to discolour and curl as they die back. Established plants of Campsis radicans and Campsis x tagliabuana 'Madame Galen' are quite hardy and typically suffer only cosmetic tip damage in UK winters, recovering fully by summer. The emerging spring shoots in April and May are also vulnerable to late frosts, which can curl and blacken the tender new growth.

What to do

Do not cut back cold or frost-damaged shoots until April when new growth confirms the extent of damage. Newly planted campsis should be protected in the first winter with a fleece wrapping over the entire plant and a deep bark mulch around the base. Cover emerging spring growth with fleece on nights when frost is forecast in April and May. Established plants on a south or west-facing wall require no winter protection in most UK conditions.

Drought stress

Campsis is moderately drought-tolerant once established in the ground but newly planted specimens in their first two seasons need regular watering before their root systems are deep enough to access moisture from a wider area. The pinnate leaves curl and develop brown margins when the root zone dries out significantly; wall-base soils at the foot of south-facing walls are particularly prone to drying out in summer. Established campsis against a warm wall in average UK garden soil rarely needs supplementary watering after the first two years.

What to do

Water newly planted campsis regularly during the first two summers; water when the top 10 cm of soil is dry. Apply a deep bark mulch (10 cm) around the root zone to conserve moisture; extend the mulch well beyond the drip line of the plant. Wall-base soil against a south-facing wall can be very dry even in wet UK summers; ensure adequate mulching and occasional watering at the base of plants in these positions.

Waterlogging

Campsis does not thrive in waterlogged or persistently wet soil; root rot can develop in saturated conditions, causing yellowing, wilting, and leaf curl that does not respond to watering. Waterlogging is rarely a serious problem for campsis in well-managed UK garden conditions, but in heavy clay soils without drainage improvement or in low-lying positions that flood in winter, root damage can weaken or kill the plant. The problem is more common in container-grown campsis where drainage holes may be blocked.

What to do

Ensure good drainage at planting; incorporate grit into heavy or compacted soils. Avoid low-lying, frost-pocket positions that also tend to have poor drainage. In containers, ensure drainage holes are clear and do not allow the pot to sit in standing water. Campsis is far less sensitive to wet conditions than Mediterranean wall shrubs such as ceanothus and fremontodendron but still performs best in well-drained soil.

Frequently asked questions

Why are my campsis leaves curling?

Campsis leaves curl most commonly because of aphids on the pinnate leaves and shoot tips in spring and summer (the most common cause), cold damage from hard winter frost or late spring frosts on emerging growth, drought stress in newly planted specimens or against dry south-facing walls, or waterlogging causing root rot. Established plants on a warm south or west-facing wall with reasonable moisture are generally trouble-free.

Why is my campsis not flowering?

Campsis fails to flower in the UK most commonly because the position is not warm and sunny enough (a south or south-west wall in full sun is essential), the plant is too young (three to five years of establishment is needed before flowering begins), or it has been pruned in spring or summer rather than late winter (campsis flowers on the current year's growth; pruning in spring removes the flower buds). Feed with potassium-rich fertiliser from June; avoid nitrogen-rich feeds that produce leafy growth at the expense of flowers.

Is campsis hardy in the UK?

Campsis radicans is fully hardy throughout the UK to at least -20°C when established. The hybrid 'Madame Galen' is hardy to about -15°C and is reliably perennial on a sheltered wall in most UK gardens. Campsis grandiflora is less hardy (to about -10 to -15°C) and best restricted to the mildest UK positions. Newly planted specimens need winter fleece protection in their first year before establishing a robust root system.

How do I prune campsis in the UK?

Prune in late winter (February to March): cut all new side shoots back to two to four buds from the permanent main framework. Do not prune in spring or summer as this removes developing flower buds. In the first few years, train main stems horizontally to build the permanent framework. Hard renovation of overgrown plants in February is possible (cut back to within 1 m of the ground) but delays flowering for two to three seasons.