Why are my clematis leaves curling?

Clematis leaves curl most commonly due to clematis wilt, aphids, or drought stress. Clematis wilt (caused by the fungal pathogen Phoma clematidina) is the most feared clematis problem: it causes the leaves and stems to wilt and blacken suddenly, with the collapse starting at the growing tips and working downward; the collapsed tissue often twists and curls as it dies; the good news is that the root system and underground buds are usually unaffected and the plant regrows from below soil level. Aphids cluster on the undersides of the young leaves and growing tips in spring and early summer, causing the tender leaves to curl around the colony; they are often present in large numbers on the vigorous new growth of clematis. Drought stress causes the leaves to wilt, curl, and the plant to decline, particularly in the first few years after planting when the root system is not yet deep enough to access subsoil moisture. Powdery mildew causes a white coating on the leaves alongside distortion and curling in warm, humid conditions. Earwigs chew holes in the leaves and flowers of clematis at night, creating irregular damage that can cause the remaining tissue to distort and curl.

What is clematis wilt and will my plant recover?

Clematis wilt is a fungal disease caused by Phoma clematidina (formerly Ascochyta clematidina) that causes the sudden collapse and blackening of one or more stems on a clematis vine. The stems wilt rapidly and the leaves turn black, curl, and die, beginning at the tips and working downward to the point where the stem enters the soil or joins the main trunk. The fungal pathogen enters through wounds or natural openings in the stem tissue and blocks water movement through the stem, causing the rapid above-ground collapse. Clematis wilt most commonly affects large-flowered hybrid clematis varieties (particularly those in pruning groups 2 and 3); small-flowered species such as Clematis montana, Clematis tangutica, and Clematis viticella have significantly better resistance to wilt. Whether a plant recovers depends on whether the fungus has penetrated below soil level: because clematis is planted deeply (the crown 2 to 3 inches below the soil surface), there are usually dormant buds below the infection that can re-shoot once the diseased stems are removed. Cut all wilted stems back to soil level or below, disinfecting the pruning shears between cuts. Remove and dispose of all affected stems; do not compost them. New shoots almost always emerge from below soil level within 4 to 6 weeks. Do not confuse clematis wilt with the normal dieback of clematis stems in autumn, which is gradual and affects all stems evenly rather than collapsing suddenly from the tips.

Why are my clematis leaves curling and going white?

Clematis leaves curling alongside a white powdery coating on the leaf surfaces indicate powdery mildew, which is a common and cosmetically damaging problem on clematis in warm, humid summer conditions. Powdery mildew on clematis is caused by Erysiphe aquilegiae var. ranunculi and related Erysiphe species that are specific to clematis and related plants. The white, powder-like coating (fungal mycelium and spores) appears on both the upper and lower leaf surfaces, and affected leaves curl, distort, and may yellow and drop prematurely. Unlike most fungal diseases, powdery mildew does not require wet foliage to germinate; it thrives in warm days with high nighttime humidity and poor air circulation. The large-flowered hybrid clematis varieties are more susceptible than small-flowered species clematis. Treat by removing the most affected leaves and applying potassium bicarbonate, neem oil, or sulfur-based fungicide to all leaf surfaces weekly; these slow the spread but do not eliminate existing infection. Improve air circulation by training the stems to avoid congestion. Choose mildew-resistant clematis varieties for future plantings: C. viticella and its hybrids have significantly better mildew resistance than the large-flowered hybrids. Avoid overhead watering and do not apply high-nitrogen fertilizer, which produces the soft, susceptible growth that mildew colonizes most readily.

Clematis Leaves Curling — Why It Happens and How to Fix It

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At a glance

Stems wilting and blackening from the tip downward suddenly: Clematis wilt; cut all affected stems to soil level and wait for regrowth
New growth curling with aphids on undersides in spring: Aphids; blast with water and treat with insecticidal soap
Leaves wilting and curling with dry soil: Drought stress; water deeply and keep roots cool with mulch
White powdery coating on leaves with curling and distortion: Powdery mildew; treat with potassium bicarbonate or neem oil weekly
Leaves with ragged holes and curled remaining tissue: Earwigs; set traps or apply barrier

Why clematis leaves curl

Clematis (Clematis species and hybrids) are among the most popular and widely grown climbing plants, valued for their large flowers in purple, blue, pink, red, and white across a range of flowering seasons. They are generally easy to grow once established but have two problems that cause particular anxiety: clematis wilt, which causes sudden and dramatic collapse of the stems, and powdery mildew, which disfigures the foliage in summer. Both are manageable, and in the case of clematis wilt, the plant almost always recovers from below soil level even after total above-ground collapse.

Cause 1: Clematis wilt

Signs: One or more stems collapse suddenly, with the leaves wilting, turning black, and curling as they die. The collapse begins at the tips and works downward to the base of the stem. The affected stems are clearly dead while other parts of the plant may still appear healthy. The sudden, dramatic nature of the collapse is distinctive. Most common on large-flowered hybrid varieties in spring and early summer when the plant is growing rapidly.

Why it happens: Clematis wilt is caused by the fungal pathogen Phoma clematidina, which enters through stem damage (from wind, mechanical injury, or insect feeding) and blocks water movement in the stem. The infection is rapid, and the stem collapses faster than the plant can compensate. Crucially, the fungus rarely penetrates below soil level because clematis crowns are planted 2 to 3 inches below the surface, protecting the dormant buds that will produce replacement growth.

Fix: Cut all collapsed stems back to soil level, removing all affected tissue. Disinfect pruning shears between cuts with 70 percent isopropyl alcohol. Remove all cut material; do not compost it. New shoots will emerge from below-ground buds, typically within 4 to 6 weeks. Future prevention: plant with the crown 2 to 3 inches below soil to protect buds; avoid stem damage when training and tying. Wilt-resistant varieties (C. viticella and its hybrids) are an excellent choice where wilt has been a persistent problem.

Cause 2: Aphids

Signs: The new shoot tips and young leaves are curling inward in spring or early summer. Clusters of small, soft-bodied insects (green, black, or yellow) are visible inside the curled leaves and on the undersides of the affected growth. Sticky honeydew makes affected areas shiny. Ants may be present tending the colony. The damage is concentrated on the newest, most tender growth.

Why it happens: Several aphid species attack clematis, including the glasshouse potato aphid (Aulacorthum solani) and the shallot aphid. They colonize the abundant new growth that clematis produces in spring and early summer, building rapidly in warm weather. The leaf curl they cause shelters the colony from predators and from contact sprays, making established colonies harder to treat.

Fix: Blast the curled shoot tips with a strong jet of water to dislodge aphid colonies. Apply insecticidal soap to all affected surfaces, penetrating into the curled tips as much as possible. Repeat every 5 to 7 days for 2 to 3 applications. Avoid broad-spectrum insecticides; natural predators including ladybugs and parasitic wasps provide effective ongoing control when not disrupted by pesticides.

Cause 3: Drought stress

Signs: The leaves are wilting and curling during hot, dry weather. The soil is dry. The plant looks stressed despite what seems like adequate watering from above. Young and recently planted clematis show these symptoms most dramatically. The plant recovers after thorough deep watering. The roots may be in dry soil even if the surface appears moist.

Why it happens: Clematis follows the gardening adage "feet in the shade, head in the sun": the roots need a cool, moist root zone while the top growth is in full sun. Roots in hot, dry soil cannot supply sufficient water to the large leaf area in summer heat. Young plants that have not yet extended their root system into deeper, more consistently moist soil are most at risk. The classic advice to plant a flat stone or a neighboring low-growing shrub at the base of clematis addresses the root zone temperature issue directly.

Fix: Water deeply to soak the full root zone rather than watering shallowly more frequently. Apply a deep layer of mulch (3 to 4 inches) over the root zone to retain moisture and keep the soil cool; keep the mulch clear of the stems at the base to reduce wilt risk. Plant a low-growing ground cover or place flat stones at the base of the clematis to shade the root zone. Ensure adequate watering during the first 2 to 3 years while the root system establishes.

Cause 4: Powdery mildew

Signs: A white, powdery coating appears on the leaf surfaces alongside curling and distortion of affected leaves. The mildew may appear first on the upper or lower leaf surface and spread across the whole leaf. Affected leaves may yellow and drop. The disease is most severe in warm, humid weather with poor air circulation and is common in late summer.

Why it happens: Powdery mildew on clematis is caused by Erysiphe species specific to clematis and Ranunculaceae family plants. It thrives in the warm days and cool, humid nights common in late summer. Dense, congested growth with poor air circulation between stems accelerates the disease. Large-flowered hybrid varieties are more susceptible than small-flowered species.

Fix: Remove the most severely affected leaves. Apply potassium bicarbonate, neem oil, or a sulfur-based fungicide to all leaf surfaces weekly; these slow but do not eliminate existing infection. Train stems to improve air circulation. Choose mildew-resistant varieties (Clematis viticella hybrids) for future plantings. Avoid high-nitrogen fertilizer, which promotes the soft growth most susceptible to mildew.

Cause 5: Earwigs

Signs: The leaves have ragged, irregular holes or notches, particularly at the edges. Flower petals may also be damaged. The damage appears overnight and the plants look progressively worse through summer. The remaining leaf tissue may curl or distort around the holes. Earwigs (elongated, pincer-bearing insects) may be found sheltering in the foliage or under debris near the plant during the day.

Why it happens: Earwigs feed on clematis leaves and flowers at night, causing the characteristic ragged damage that can cause the remaining leaf tissue to curl. Despite their reputation, earwigs are generally more beneficial than harmful in the garden (they eat aphid eggs and other pests), but in high populations they cause noticeable cosmetic damage to clematis foliage and flowers.

Fix: Set earwig traps: stuff small flowerpots with newspaper and place them inverted on stakes near the clematis; earwigs shelter in these during the day and can be collected and disposed of. Remove garden debris that provides daytime shelter. For severe damage, apply a pyrethrin-based insecticide in the evening when earwigs are active. Maintaining a population of ground beetles, which prey on earwigs, reduces damage naturally.

Clematis Leaves Curling