Plant problems

Why Are My Itea Leaves Curling?

Q: Why are my itea leaves curling?

Itea leaves curl most commonly in UK gardens because of drought stress (both Itea ilicifolia and Itea virginica have moderate moisture requirements and their leaves curl when the root zone dries out, particularly in the first seasons after planting and against south-facing walls), cold damage in hard winters (the semi-evergreen or deciduous leaves curl and brown at the tips and margins after hard frost or cold drying wind), or waterlogging in poorly drained soils. Two itea species are grown in UK gardens: Itea ilicifolia (Chinese itea or holly-leaved sweetspire) is an evergreen or semi-evergreen wall shrub grown for its long, drooping racemes of tiny, sweetly scented, greenish-white flowers in late summer (August to September); the leaves are glossy, dark green, and holly-like with spine-tipped teeth, and the flower racemes can reach 30 cm in length, giving the plant a graceful, elegant appearance. It is marginally hardy in the UK and is grown against sheltered south or west-facing walls in mild to moderately cold UK gardens. Itea virginica (Virginia sweetspire) is a deciduous shrub from eastern North America that produces upright racemes of small, white, fragrant flowers in June to July and spectacular autumn foliage in shades of crimson, orange, and yellow; it is significantly hardier than I. ilicifolia and can be grown in the open garden in most of the UK. The two species have quite different cultural requirements: I. ilicifolia needs good drainage and shelter; I. virginica prefers moist to reliably moist soil and tolerates waterlogging better than most shrubs.

Q: Is itea ilicifolia hardy in the UK?

Itea ilicifolia is marginally hardy in the UK; it is generally considered hardy to about -8 to -10°C in a sheltered, south or west-facing wall position, and is reliably perennial in mild, sheltered UK gardens in the south and west of England, Wales, and mild coastal or urban positions further north. In colder or more exposed UK gardens (north of the Midlands, high altitude, exposed positions), it may be damaged or killed in hard winters and is best treated as a wall shrub with winter protection in the coldest months. The combination of cold and wet is more damaging than cold alone: Itea ilicifolia in freely draining conditions against a warm wall is significantly hardier than the same plant in heavy, wet soil. Cold wind desiccates the large evergreen leaves and causes browning and curling of the leaf margins; shelter from north and east winds is important. The plant's most spectacular feature, the long, drooping flower racemes, are produced on the previous year's wood; cold damage to the stems in winter reduces the following summer's flower display. In mild UK gardens (southern England, western sheltered positions), Itea ilicifolia is a genuinely impressive wall plant that combines interesting, holly-like foliage with an extraordinary late-summer flower display and a strong honey-and-heliotrope fragrance.

Q: How do I grow itea ilicifolia in the UK?

Itea ilicifolia grows best against a sheltered south or west-facing wall in full sun to light partial shade, in moist but well-drained, fertile soil. Plant in spring (April to May) to give the plant time to establish before the first winter; water consistently in the first season. The plant does not self-cling and needs training against wires or trellis on the wall. Prune after flowering (October to November): cut back the flowered stems by about one third to maintain a neat, well-structured plant and to encourage new growth that will carry next year's flowers; do not prune in spring as this removes the developing flower buds on the previous year's stems. Feed with a balanced fertiliser in April to encourage vigorous growth. Mulch the root zone in autumn to protect the roots from frost. In colder UK areas, wrap young or recently planted specimens in horticultural fleece from November to March. The flowers are intensely fragrant at close range and from a distance on warm, still evenings; positioning the plant near a frequently used door, window, or seating area maximises the enjoyment of this feature. Itea ilicifolia is slow to flower when young; allow three to four years before expecting the full flower display on an established wall plant.

Q: How do I grow itea virginica in the UK?

Itea virginica (Virginia sweetspire) is significantly hardier than I. ilicifolia and can be grown as a freestanding shrub in the open garden throughout most of the UK; it is hardy to approximately -20°C or below and is one of the most cold-hardy shrubs in the genus. Unlike I. ilicifolia, Virginia sweetspire actually prefers moist to reliably moist soils and tolerates waterlogging; in its native habitat in eastern North America it grows at the edges of streams, ponds, and in boggy ground. It is an excellent shrub for moist, partially shaded positions in UK gardens where few other flowering shrubs thrive, and it associates naturally and well with moisture-loving plants such as astilbe, ligularia, and hostas. Plant in any moist to wet, fertile soil in sun or partial shade; no wall or special protection is needed in most UK gardens. The principal attraction in the garden season is the exceptional autumn foliage colour: the deciduous leaves turn brilliant crimson, orange-red, and yellow in October to November, often remaining on the plant for several weeks; in a good autumn year the display is comparable with the best deciduous azaleas or acers for colour intensity. The white, fragrant, upright flower racemes in June to July are also ornamental. The cultivar 'Henry's Garnet' is widely considered the finest form for UK gardens: it has larger flower racemes, more prolific and more brilliantly coloured autumn foliage, and is slightly more compact and neater in habit than the typical species.

Two itea species are grown in UK gardens with contrasting requirements: Itea ilicifolia (Chinese itea) is a marginally hardy, evergreen wall shrub with long, drooping, intensely fragrant flower racemes in August to September, grown against a sheltered south-facing wall. Itea virginica (Virginia sweetspire) is fully hardy, deciduous, prefers moist soil, and produces brilliant crimson autumn colour. Drought stress is the most common cause of leaf curl in both; cold damage is the main threat to I. ilicifolia.

Drought stress

Drought stress causes leaf curl in both itea species; the leaves curl inward along their length and the tips and margins brown when the root zone dries out. Itea ilicifolia against a south or west-facing wall is particularly vulnerable as the wall base can become very dry in summer even in average UK conditions. Newly planted specimens of both species are most vulnerable before the root system is deeply established. Itea virginica's preference for moist soil means drought stress can occur even in positions where most other shrubs would be fine.

What to do

Mulch the root zone of both species with 10 cm of composted bark every spring; this conserves moisture and is the single most effective preventive measure. Water during dry spells; I. ilicifolia against a wall needs regular monitoring in summer as wall-base soil dries rapidly. Improve the soil with well-rotted compost before planting to increase moisture retention. I. virginica in a reliably moist, partially shaded position rarely suffers drought stress; it is ideal for damp borders or waterside plantings.

Cold damage

Cold damage is the primary concern for Itea ilicifolia in UK gardens; hard frost below about -8 to -10°C browns and curls the evergreen leaves, kills stem tips, and in severe winters can kill the plant to the ground. Cold drying wind causes desiccation of the large, glossy leaves, producing brown curled margins similar to frost scorch. The long flower racemes develop on the previous year's wood; cold damage to the stems in winter reduces the following summer's display. Itea virginica, being a native of continental eastern North America, is far more cold-tolerant and is rarely damaged by frost in UK conditions.

What to do

Grow I. ilicifolia exclusively against a sheltered south or west-facing wall; the wall's thermal mass significantly reduces the frost depth reached at the root and stem base. Wrap young plants in fleece from November to March in colder UK areas. Do not prune cold-damaged growth until April or May; new growth from the base or surviving buds confirms the extent of winter damage. I. virginica needs no cold protection in any UK garden.

Waterlogging

Itea ilicifolia does not tolerate waterlogged or persistently wet soil; the roots rot in saturated conditions and the plant declines in wet winters in heavy clay or low-lying sites. Freely draining soil against a wall base is essential for reliable overwintering. Itea virginica is the opposite: it actually prefers moist to wet soil and tolerates waterlogging significantly better than most shrubs; in its native North American habitat it grows along stream banks and in boggy ground.

What to do

For I. ilicifolia: plant only in freely draining soil; add grit to clay soils before planting. A raised position against a wall (where the wall overhang deflects rain from the root zone) is ideal for winter drainage. For I. virginica: the wetter and moister the better; it is ideal for boggy, waterlogged, or reliably moist positions where most other flowering shrubs struggle.

Frequently asked questions

Why are my itea leaves curling?

Itea ilicifolia leaves curl most commonly because of drought stress (wall-base soil dries quickly in summer; mulch and water) or cold damage (frost and cold wind curl and brown the evergreen leaves; the plant regrows from the base after moderate winters). Itea virginica leaves curl because of drought stress in the growing season (it prefers moist soil; mulch and water) or from normal deciduous leaf drop and curl in autumn. The two species have very different requirements and the cause of leaf curl differs between them.

Is itea ilicifolia hardy in the UK?

Itea ilicifolia is hardy to about -8 to -10°C in a sheltered south or west-facing wall position and is reliably perennial in mild to moderately cold UK gardens. In colder or exposed positions it may be damaged or killed in hard winters; treat as a wall shrub with fleece protection in colder UK areas. The combination of cold and wet is most damaging; freely draining soil is essential. The extraordinary fragrant flower racemes in August to September make the effort worthwhile in suitable positions.

How do I grow itea ilicifolia in the UK?

Grow against a sheltered south or west-facing wall in full sun to light shade, in moist but well-drained, fertile soil. Train on wires or trellis. Prune after flowering in October to November; cut flowered stems back by one third. Feed in April. Mulch in autumn. Wrap in fleece from November to March in colder areas. Allow three to four years before expecting the full display of long, drooping, intensely fragrant flower racemes.

How do I grow itea virginica in the UK?

Grow as a freestanding shrub in moist to wet, fertile soil in sun or partial shade; no wall or cold protection needed. Ideal for boggy, waterlogged, or reliably moist borders and waterside plantings where few other flowering shrubs thrive. The cultivar 'Henry's Garnet' is the finest form for UK gardens with larger flower racemes and outstanding crimson, orange, and yellow autumn colour in October to November.