Plant problems

Why Are My Tetrapanax Leaves Curling?

Q: Why are my tetrapanax leaves curling?

Tetrapanax papyrifer (rice paper plant or Chinese rice paper plant) leaves curl most commonly in the UK because of frost damage, drought stress on the enormous leaves in hot or windy summer conditions, or wind scorch on the large, deeply lobed foliage. Tetrapanax papyrifer is a large, suckering, tree-like shrub from Taiwan and southern China; it is grown in UK gardens for its extraordinarily dramatic, deeply lobed, palmate leaves, which can reach 60 to 90 cm across on a mature, well-established plant in the mildest UK conditions; the white, felted undersides of the leaves and the thick, pale grey stems create an exotic, tropical-jungle appearance. The leaves curl and the tips and margins brown when the plant is stressed; the most common causes are frost damage to the emerging or expanded leaves in spring, drought stress in summer (the huge leaves transpire enormous quantities of water and curl inward when the root zone dries out), and wind scorch (the large, soft leaves tear and curl when exposed to strong winds). In UK conditions, tetrapanax behaves as a root-hardy perennial in all but the coldest gardens: the top growth is killed by hard frost in most UK winters, but the plant regrows vigorously from the rootstock in spring, and from its extensive underground suckering roots, sometimes at considerable distance from the parent plant. In the very mildest UK gardens (sheltered coastal Cornwall, Devon, and sheltered urban gardens in south London), tetrapanax can retain significant top growth through mild winters and develop a permanent trunk, eventually reaching 4 to 5 m in height.

Q: Is tetrapanax hardy in the UK?

Tetrapanax papyrifer is root-hardy throughout most of the UK; the rootstock and suckering underground stems survive winters that kill the top growth entirely, and the plant regrows vigorously in spring. The rootstock is hardy to about -10 to -15°C in well-drained conditions with a thick mulch; in severe winters below about -15°C, the rootstock itself may be damaged or killed in exposed positions, though this is uncommon in most UK gardens. The top growth (stems and leaves) is far less hardy than the rootstock and is typically killed by the first hard frost of autumn in most UK positions. In the mildest UK gardens (sheltered urban positions in London, mild coastal gardens in Cornwall, Devon, and south Wales), tetrapanax can retain a permanent woody trunk through mild winters; in such gardens it eventually develops into a substantial tree-like shrub with enormous leaves. The cultivar 'Rex' is typically described as producing the largest leaves and is the most commonly available form in UK garden centres; it does not differ significantly from the species in terms of hardiness. The key to maximising the exotic, dramatic appearance of tetrapanax in a UK garden is: plant in a sheltered, warm position where the top growth survives as many winters as possible, to allow the stems to build up height; protect the rootstock in colder gardens with a deep mulch in winter; and accept that even after severe winters that kill the top growth, the plant will regrow to produce impressive leaves from the base in the same season.

Q: How do I grow tetrapanax in the UK?

Tetrapanax grows best in a warm, sheltered position in full sun to light partial shade, in moist, fertile, well-drained soil with generous feeding throughout the growing season. Unlike many exotic-looking plants, tetrapanax is not a drought-adapted plant; it comes from humid, subtropical forest environments and needs consistent moisture to produce its enormous leaves to their full potential. Choose the warmest, most sheltered position available: a south or west-facing wall, a sheltered courtyard, or a position surrounded by other large plants that create a warm, humid microclimate. The plant is very tolerant of shade and produces large, dramatic leaves even in quite shaded positions, though the stems become more drawn and the overall size is reduced compared with a sunny, open position. Feed generously: tetrapanax is a high-fertility plant that benefits from heavy applications of a balanced fertiliser in April and May when the new growth is developing, and from monthly liquid feeds through the growing season. Mulch the root zone deeply (15 to 20 cm of composted bark or well-rotted compost) in spring to conserve moisture and in autumn to protect the rootstock from frost. Water during dry spells; the enormous leaves lose moisture rapidly and drought stress quickly causes the leaves to curl and look unhappy. Be prepared for the plant to spread by suckering over a wide area; unwanted suckers can be removed in spring by cutting through the connecting root with a spade, but complete containment of tetrapanax is difficult, and attempting to eliminate it once established is very challenging as the roots are deep and extensive.

Tetrapanax papyrifer (rice paper plant) is one of the most dramatic exotic-looking UK garden plants: deeply lobed, palmate leaves to 90 cm across on a suckering shrub that regrows vigorously each year. It is root-hardy throughout most of the UK but the top growth is killed by frost in most winters. Frost damage, drought stress on the enormous leaves, and wind scorch are the most common causes of leaf curl; the plant's aggressive suckering is the most significant management challenge.

Frost damage

Frost damage is the most common cause of leaf curl and blackening in tetrapanax in UK gardens. The large, soft leaves are killed at the first hard frost of autumn, turning black and collapsing almost overnight; the stems are progressively killed down to the ground in hard winters. New leaves emerging in spring from regrowth shoots are also vulnerable to late spring frosts, which turn the soft young foliage black at the tips. The rootstock, being underground, is significantly more frost-tolerant and typically survives all but the most severe UK winters to regenerate fresh growth in spring.

What to do

Apply a thick mulch (15 to 20 cm of composted bark, straw, or dry leaves) over the root zone in November before the first hard frost; this is the most important winter protection measure. In sheltered UK positions where the stems may survive mild winters, wrap the stems individually with several layers of horticultural fleece from November to March. Do not cut back frost-killed top growth until April when new growth from the base confirms the extent of winter damage. In spring, cut all dead stems to the ground to make way for the vigorous fresh regrowth.

Drought stress

The enormous leaves of tetrapanax transpire very large quantities of water in warm weather; the whole plant can wilt and the leaves curl inward dramatically within hours if the root zone dries out significantly in summer. This is particularly a problem in hot, sunny spells or when the plant is in a sheltered, warm position where temperature builds up rapidly. Container-grown tetrapanax is especially vulnerable as the restricted root volume dries out very quickly. Even in the ground, tetrapanax in freely draining or shallow soils requires regular summer watering to maintain the magnificent, fully expanded leaves.

What to do

Mulch the root zone deeply (10 cm of composted bark) in spring and extend the mulch well beyond the drip line of the plant. Water during dry spells; do not allow the soil to dry out significantly in summer. Container-grown tetrapanax may need watering twice daily in very warm weather; move containers to a less sunny position during the hottest part of the day if wilting is persistent. Feed generously with a balanced fertiliser through the growing season to support the energetic production of large leaves.

Wind scorch

The large, thin-textured, deeply lobed leaves of tetrapanax are highly susceptible to wind scorch and mechanical damage in strong winds; the leaves tear along the lobes, curl at the margins, and develop brown, papery tips in exposed positions. Wind damage is most severe in spring when the fresh, young leaves are just expanding and have not yet thickened and toughened; a single windy night in May can leave a tetrapanax looking very tatty for much of the season. The plant naturally grows in sheltered, humid forest environments and is poorly adapted to exposed UK garden positions.

What to do

Choose the most sheltered position available: behind a wall, fence, hedge, or group of large plants that breaks the wind. A sheltered courtyard is ideal. Do not plant in exposed, windy positions; the leaves will be tatty and damaged throughout the season regardless of other care. Wind-damaged leaves cannot recover; new leaves produced later in the season will be undamaged if the wind exposure is reduced. Individual large leaves can be temporarily supported in windy periods with a light bamboo cane tied loosely to the leaf stem.

Suckering and spread

Tetrapanax spreads aggressively by underground suckering roots that emerge at considerable distance from the parent plant; this is a feature rather than a problem in large gardens seeking a dramatic tropical colony effect, but can be challenging to manage in smaller gardens. The roots are deep and brittle, breaking easily when dug; root fragments regenerate readily, making complete eradication very difficult once the plant is established. Suckers can emerge through paving, gravel, and other hard surfaces as well as through lawn and garden soil.

What to do

Install a deep root barrier (minimum 60 to 70 cm depth, polypropylene) at planting if spread control is important; this is most effective before the root system becomes extensive. Remove emerging suckers by cutting through the connecting root with a spade as far from the sucker as possible; repeat whenever suckers appear (every 2 to 3 weeks in the growing season) to exhaust the energy in the root fragments. Never rotary-till around tetrapanax as this chops the roots into fragments, each of which regenerates. Accept that complete containment of an established tetrapanax is very challenging.

Frequently asked questions

Why are my tetrapanax leaves curling?

Tetrapanax leaves curl most commonly because of frost damage (the large, soft leaves are killed at the first hard autumn frost and new spring growth is vulnerable to late frosts), drought stress (the enormous leaves transpire heavily and curl dramatically when the root zone dries out in summer), or wind scorch (the thin-textured leaves tear and curl in strong winds). In a warm, sheltered, moist position, the leaves unfurl to their full dramatic potential.

Is tetrapanax hardy in the UK?

Tetrapanax is root-hardy throughout most of the UK; the rootstock survives to about -10 to -15°C under a deep mulch and regrows vigorously from the base each spring. The top growth is killed by hard frost in most UK winters. In the very mildest gardens (sheltered urban London, coastal Cornwall and Devon), the stems can survive mild winters and the plant gradually builds height. Deep mulching of the root zone in November is the most important winter protection measure.

How do I grow tetrapanax in the UK?

Grow in a warm, sheltered position (south or west-facing wall, sheltered courtyard) in full sun to light shade, in moist, fertile, well-drained soil. Mulch deeply in spring; water during dry spells; feed generously throughout the growing season. Protect the rootstock with a 15 to 20 cm bark or straw mulch in November. Cut dead top growth to the ground in spring. Be prepared to manage spreading suckers; install a root barrier at planting if control is important.

Can I control tetrapanax spread?

Complete control is very difficult once tetrapanax is established. The most effective approach is a deep polypropylene root barrier (60 to 70 cm) installed at planting. For established plants, remove suckers as they appear by cutting through the root with a spade; repeat every few weeks to exhaust root fragments. Never rotary-till around the plant. In the right large garden setting, the suckering colony effect is part of the plant's dramatic appeal.