Plant problems

Why Are My Abutilon Leaves Curling?

Q: Why are my abutilon leaves curling?

Abutilon (flowering maple or Chinese lantern) leaves curl most commonly in the UK because of whitefly infestation, cold damage, red spider mite, or abutilon mosaic virus. Abutilon is a genus of shrubs and small trees from tropical and subtropical regions of South America, Africa, and Asia; the species most commonly grown in UK gardens as wall shrubs or container plants include Abutilon megapotamicum (trailing abutilon) with distinctive lantern-shaped flowers in red and yellow from June to October, Abutilon vitifolium (vine-leaved abutilon) with large, soft, five-petalled mauve or white flowers in May to June, and various hybrid abutilons in shades of orange, yellow, pink, red, and cream. All are marginally hardy in the UK and grow best in warm, sheltered positions in the south and west; Abutilon vitifolium is the most hardy of the commonly grown species, surviving to about -10°C in ideal conditions. Whitefly (greenhouse whitefly, Trialeurodes vaporariorum) is the most common pest on abutilon in the UK, colonising the leaf undersides of all species; the tiny white-winged adults fly up in a cloud when disturbed, the larvae produce honeydew and sooty mould, and the leaves yellow and curl under heavy infestation. Cold damage on abutilon causes the large, soft leaves to blacken, wilt, and curl when temperatures fall below the plant's tolerance; the extent of damage depends on species and position. Red spider mite (Tetranychus urticae) causes fine speckling, bronzing, and curling of the leaves in hot, dry conditions in summer. Abutilon mosaic virus causes distinctive yellow mottling, leaf distortion, and curl that does not respond to cultural treatments.

Q: Is abutilon hardy in the UK?

The hardiness of abutilon in the UK varies significantly by species: Abutilon vitifolium (vine-leaved abutilon) is the hardiest species commonly grown in UK gardens, surviving to about -8 to -10°C in ideal, well-drained conditions against a sheltered south or west-facing wall; it is reliably perennial in sheltered gardens in southern and western England and can reach 4 to 6 m against a warm wall over several years. Abutilon megapotamicum (trailing abutilon) is less hardy, surviving to about -5 to -8°C; it does best against a warm wall in mild UK gardens and may be killed to the ground in cold winters, regrowing from the base in spring if the crown survives. Hybrid abutilons (most commonly sold as pot plants or conservatory shrubs with orange, yellow, or red flowers) are generally the least hardy and should be considered half-hardy in most UK positions; they are best grown in containers that can be brought into a frost-free conservatory, cool greenhouse, or porch for winter, returning outdoors in May after the last frost. Abutilon vitifolium is the best choice for a permanent outdoor UK wall shrub in the south and west; it flowers generously in its first few years after planting but is short-lived (typically 5 to 8 years) and should be replaced when it becomes very woody and less floriferous. The variegated hybrid Abutilon 'Souvenir de Bonn' (large orange flowers, leaves edged cream) is widely grown as a container plant and is not hardy outdoors in the UK.

Q: How do I grow abutilon outdoors in the UK?

Abutilon vitifolium is the most suitable abutilon for outdoor UK growing; plant against a sheltered south or west-facing wall in well-drained, moderately fertile soil in full sun or very light dappled shade. The wall provides reflected warmth and shelter from cold winds, which are both critical for reliable flowering and winter survival. Plant in spring after the last frost in well-prepared, free-draining soil; incorporate some well-rotted compost or leaf mould into the planting hole to improve fertility without waterlogging. The plant grows quickly in its first few years and should be trained against the wall with wires or trellis; the main stems can be tied in to fill the available space. Feed with a balanced fertiliser in spring and a potassium-rich fertiliser (such as liquid tomato feed) monthly from June to August to encourage the production of flowers rather than leafy growth. Mulch the root zone in autumn with composted bark to protect the roots from frost. Prune in spring (March to April): cut back any frost-damaged or dead stems to healthy, live tissue, and lightly reshape the plant to maintain a good wall covering. Abutilon vitifolium flowers abundantly in May and June on wood formed the previous season; avoid heavy pruning in late summer or autumn, which removes next year's flowering wood. In colder or more northerly UK gardens, hybrid abutilons can be grown in large containers and overwintered in a frost-free conservatory or cool greenhouse; bring outdoors when nighttime temperatures are reliably above 5°C in late April or May.

Q: What is abutilon mosaic virus?

Abutilon mosaic virus (AbMV) is a gemini virus that infects abutilon plants, causing distinctive pale yellow to bright yellow mottling, streaking, and variegation on the leaves, often with associated leaf distortion, curling, and reduced plant vigour. The virus is transmitted primarily by the whitefly Bemisia tabaci (tobacco whitefly or silverleaf whitefly) in a persistent, semi-persistent manner; it is also transmitted through vegetative propagation (cuttings taken from infected plants). In some abutilon varieties, the symptoms of AbMV have historically been regarded as ornamental: some plants sold as 'variegated abutilon' are in fact AbMV-infected plants whose mottled, yellow-green foliage is the result of viral infection rather than true genetic variegation; these infected plants were deliberately propagated and sold for their attractive mottled appearance. In UK gardens, AbMV-infected plants are less common than in warmer climates where Bemisia tabaci is established outdoors; UK transmission primarily occurs through infected cuttings or through greenhouse whitefly (Trialeurodes vaporariorum), though Bemisia tabaci can occasionally arrive on imported plant material. There is no cure for abutilon mosaic virus: infected plants cannot be cured, and the virus spreads if whiteflies are present. Mildly infected plants with attractive variegation and otherwise healthy growth can be retained if whitefly populations are controlled; severely infected plants that are stunted, distorted, and performing poorly should be removed and destroyed. Do not propagate from virus-infected plants.

Abutilon (flowering maple or Chinese lantern) includes several marginally hardy shrubs grown in UK gardens and conservatories for their exotic, lantern-shaped or open-cupped flowers in shades of orange, red, yellow, pink, and cream. Abutilon vitifolium is the most reliably hardy for outdoor UK walls; hybrid abutilons are best as container plants overwintered under glass. Whitefly on the large, soft leaves and cold damage to the top growth in winter are the most common causes of leaf curl.

Whitefly

Greenhouse whitefly (Trialeurodes vaporariorum) is the most common pest on abutilon in the UK; the tiny, white-winged adults colonise the leaf undersides and fly up in a cloud when disturbed. The scale-like larvae feed on leaf sap, producing honeydew that supports sooty mould growth on the leaf surfaces below; heavily infested leaves yellow, curl, and drop prematurely. Whitefly populations build up rapidly in warm, sheltered conditions; plants in conservatories, against warm walls, or inside glasshouses are particularly vulnerable. Outdoor plants in cool, breezy positions are less affected.

What to do

Introduce the parasitoid wasp Encarsia formosa as a biological control in glasshouse or conservatory conditions; this is the most effective and sustainable control for whitefly on indoor or sheltered wall plants. Apply insecticidal soap spray to all leaf undersides where larvae are feeding; the spray must contact the insects directly and should be repeated every 7 to 10 days. Use yellow sticky traps to monitor and reduce adult whitefly populations. Improve ventilation around conservatory plants to reduce the warm, still conditions that favour whitefly reproduction. Remove heavily infested shoots to reduce the larval population quickly.

Cold damage

Cold damage causes the large, thin-textured leaves of abutilon to blacken, wilt, and curl when temperatures fall below the plant's tolerance; the extent of damage depends on the species and position. Abutilon vitifolium can survive UK winters to about -10°C against a sheltered wall; hybrid abutilons and Abutilon megapotamicum are damaged below about -5°C. In a typical UK winter outside the mildest gardens, most hybrid abutilons will have their top growth killed and should be overwintered under glass. The roots and crown of hardy species may survive even when the top growth is killed; new shoots emerge from the crown in spring.

What to do

Grow outdoor abutilon against the warmest available wall (south or west-facing) in well-drained soil. Mulch the root zone with composted bark in late autumn. Do not prune cold-damaged stems until April when new growth confirms the extent of damage. Bring container-grown hybrid abutilons into a frost-free conservatory, porch, or cool greenhouse before the first autumn frost (typically October); return outdoors in late April or May when nighttime temperatures are reliably above 5°C. Take semi-ripe cuttings from outdoor abutilons in summer as insurance against winter losses.

Red spider mite

Red spider mite (Tetranychus urticae) colonises the leaf undersides of abutilon in hot, dry summer conditions, causing fine pale speckling on the upper leaf surface (the mites' feeding punctures), progressive bronzing of the leaf, and curling of the leaf margins; heavy infestations produce fine silken webbing over the leaf undersides and growing tips. Red spider mite is most damaging on plants in hot, sheltered, dry positions in summer; outdoor plants in less sheltered positions with good air circulation and adequate moisture are less vulnerable.

What to do

Mist the leaf undersides with water in hot, dry weather; red spider mite thrives in hot, dry conditions and high humidity disrupts population growth. Apply predatory mite Phytoseiulus persimilis as a biological control when temperatures are consistently above 16°C. Apply insecticidal soap or neem oil spray to all leaf surfaces, focusing on the undersides where mites congregate; repeat every 7 to 10 days. Ensure the plant is adequately watered during dry spells; moisture-stressed plants are more susceptible to spider mite damage.

Abutilon mosaic virus

Abutilon mosaic virus (AbMV) causes distinctive yellow mottling, streaking, and variegation on the leaves, often with associated leaf distortion, curling, and reduced vigour; the symptoms are transmitted through infected cuttings and by whitefly. Interestingly, some 'variegated abutilon' plants sold in garden centres are in fact AbMV-infected plants whose mottled yellow-green foliage is the result of viral infection rather than true genetic variegation; mildly infected plants with attractive mottling and otherwise good growth can be retained, but should not be propagated from. There is no cure for AbMV.

What to do

Control whitefly populations (the primary virus vector) to limit spread within a collection. Do not take cuttings from any plant suspected of virus infection. Remove and destroy plants that are severely stunted, distorted, or performing poorly due to virus. Plants with attractive mottled variegation that are growing vigorously can be retained; just avoid propagating them and control whitefly to prevent spread to other plants.

Frequently asked questions

Why are my abutilon leaves curling?

Abutilon leaves curl most commonly because of whitefly (tiny white-winged insects on leaf undersides; associated yellowing and sooty mould), cold damage (large soft leaves blacken, wilt, and curl below the species' frost threshold), red spider mite in hot dry conditions (fine speckling and bronzing with webbing on leaf undersides), or abutilon mosaic virus (yellow mottling, distortion, and curl transmitted by whitefly and infected cuttings). Whitefly is the most common cause on plants in conservatories and sheltered wall positions.

Is abutilon hardy in the UK?

Abutilon vitifolium is the hardiest species for UK outdoor growing, surviving to about -8 to -10°C against a sheltered south or west-facing wall. Abutilon megapotamicum survives to about -5 to -8°C. Hybrid abutilons are half-hardy and need frost-free overwintering under glass in most UK gardens. All benefit from a warm, sheltered wall position; outdoor survival depends as much on drainage and shelter as on raw temperature.

How do I grow abutilon outdoors in the UK?

Plant Abutilon vitifolium against a sheltered south or west-facing wall in spring, in well-drained, moderately fertile soil in full sun. Train against wires or trellis. Feed with potassium-rich fertiliser monthly in summer. Mulch in autumn. Prune in spring: remove dead and frost-damaged stems; avoid heavy pruning in late summer. Abutilon vitifolium is fast-growing but short-lived (5 to 8 years); keep young replacement plants from summer cuttings.

What is abutilon mosaic virus?

Abutilon mosaic virus (AbMV) causes yellow mottling, leaf distortion, and curling; it is transmitted by whitefly and infected cuttings. Some mottled 'variegated' abutilons sold in garden centres are actually virus-infected plants; mildly affected plants with attractive mottling can be kept but should not be propagated from. Severely affected, stunted, and distorted plants should be removed and destroyed. Control whitefly to limit spread.