Plant problems

Why Are My Hedychium Leaves Curling?

Q: Why are my hedychium leaves curling?

Hedychium (ginger lily) leaves curl most commonly in the UK because of drought stress, cold wind scorch, cold damage to the emerging shoots or to the whole plant in hard winters, or waterlogging of the rhizomes. Hedychium is a genus of large, tropical-looking, rhizomatous perennials from the Himalayan foothills, southern China, and South-East Asia; the tall, cane-like stems bear large, paddle-shaped leaves and are topped with showy flower spikes in late summer (August to September) in shades of white, cream, yellow, orange, red, and bicolours, often intensely fragrant. The most commonly grown species in UK gardens include Hedychium gardnerianum (Kahili ginger, yellow flowers with red filaments, strongly fragrant, to 1.5 to 2 m), Hedychium coccineum (red flowers, to 1.5 m), Hedychium forrestii (white flowers, to 2 m), and Hedychium densiflorum (small orange flowers, to 2 m). Drought stress is the most common cause of leaf curl in UK hedychium: the large, paddle-shaped leaves lose moisture rapidly and curl inward when the root zone dries out, particularly in containers where the restricted root volume dries out quickly in warm weather. Cold wind scorch causes the leaf edges and tips to turn brown and curl, particularly on the large leaves of container-grown specimens moved outdoors in spring before being thoroughly hardened off. Cold damage in hard UK winters kills the top growth of all but the hardiest hedychium species to the ground and may damage the rhizomes if they are not protected.

Q: Is hedychium hardy in the UK?

The hardiness of hedychium in the UK varies significantly between species. Hedychium densiflorum and its cultivars (particularly 'Assam Orange') are considered the hardiest species widely grown in UK gardens, surviving to about -10 to -15°C in well-drained, sheltered conditions with the rhizomes mulched; they are reliably perennial in most of southern England and in sheltered, well-drained positions in other parts of the UK. Hedychium forrestii is similarly hardy. Hedychium gardnerianum (Kahili ginger) and Hedychium coccineum are slightly less hardy (to about -5 to -8°C) and are best regarded as borderline hardy outside the mildest UK gardens; they require deep mulching of the rhizomes in autumn and may be killed in hard UK winters. In the mildest UK gardens (coastal Cornwall, Devon, south Wales, urban south London), Hedychium gardnerianum can be grown as a permanently established outdoor plant and develops impressive clumps over many years; it is naturalised in parts of the Azores, Madeira, and the Canary Islands and can become invasive in mild, frost-free conditions. In less mild UK gardens, grow tender hedychium species in large containers that can be brought into a frost-free conservatory or cool greenhouse for winter; container-grown plants can be dried off and stored almost dry in a cool greenhouse over winter and restarted in spring. The key to winter survival for outdoor hedychium is: well-drained soil (wet rhizomes rot at temperatures well above the frost threshold), and a thick mulch (15 to 20 cm of composted bark or straw) applied over the root zone before the first frost.

Q: How do I grow hedychium in the UK?

Hedychium grows best in a warm, sheltered position in full sun to light dappled shade, in consistently moist but well-drained, humus-rich, fertile soil. The conditions needed are similar to those that suit cannas and dahlias: a warm, sheltered border with rich, moisture-retentive but freely draining soil, and a long, warm growing season for the tall, cane-like stems to develop and flower. Plant the rhizomes horizontally at a depth of about 5 to 8 cm in spring (April or May) after the last frost, when the soil temperature has risen to at least 10°C. Space rhizomes 60 to 90 cm apart; the plants spread by producing new rhizomes and will fill the available space over several years. Feed with a balanced fertiliser monthly from May to August to support the vigorous growth; a high-potassium feed from July onwards encourages flowering. Mulch the soil surface with composted bark or well-rotted compost in spring to conserve moisture; this is essential for the sustained soil moisture that hedychium needs throughout the growing season. Water regularly in dry spells; the large, paddle-shaped leaves transpire heavily in warm weather and drought stress quickly causes leaf curl and reduced flowering. In late autumn (October to November), after the first frosts have killed the top growth, cut the dead stems to the ground and apply a deep mulch of composted bark (15 to 20 cm) over the root zone to protect the rhizomes from frost. In containers: use a large pot (minimum 40 cm diameter) with rich, moisture-retentive compost; water frequently in summer (daily in hot weather); bring indoors before the first autumn frost.

Q: When does hedychium flower in the UK?

Hedychium typically flowers in the UK from late August to September or early October, making it one of the latest-flowering of all the exotic-looking UK border plants. The flower timing depends on the species, the warmth of the summer, and the maturity of the clump: Hedychium densiflorum cultivars tend to flower first (from August); Hedychium gardnerianum and Hedychium forrestii flower in August to September; Hedychium coccineum and some hybrids may not begin flowering until September or October in the UK, and in a cool summer may be cut by frost before the flowers open. The late-summer to autumn flowering season is one of hedychium's great assets in the UK garden; at a time when many border plants are past their best, hedychium provides dramatic, exotic-looking flower spikes above tropical-looking foliage, often with outstanding fragrance. The fragrance of Hedychium gardnerianum (a clean, jasmine-like scent) and Hedychium coronarium (white flowers, intensely fragrant, though less commonly grown outdoors in the UK) is particularly outstanding. For the best flowering performance in the UK, hedychium needs a long, warm, sunny growing season: a warm summer produces more flowers, earlier, on better-developed spikes than a cool, cloudy summer. Against a south-facing wall or fence in a sheltered urban garden, or in a warm greenhouse or conservatory, hedychium flowers more reliably and abundantly than in a cool, exposed outdoor position.

Hedychium (ginger lily) is a group of large, tropical-looking rhizomatous perennials from the Himalayan foothills, grown in UK gardens for their dramatic paddle-shaped leaves and showy, often fragrant flower spikes from August to October. The most commonly grown species are Hedychium densiflorum (hardiest, orange flowers), Hedychium gardnerianum (yellow, strongly fragrant), and Hedychium coccineum (red). Drought stress and cold damage are the most common causes of leaf curl in UK gardens.

Drought stress

Drought stress is the most common cause of leaf curl in hedychium in UK gardens; the large, paddle-shaped leaves are thin-textured and lose moisture rapidly, and the plants curl their leaves inward when the root zone dries out. Container-grown hedychium is particularly vulnerable as the restricted root volume dries out quickly in warm summer weather, sometimes requiring watering twice daily in very hot conditions. Even in the ground, hedychium in freely draining soils or in prolonged dry UK summers can suffer drought stress that reduces both leaf condition and flower production.

What to do

Water container-grown hedychium very regularly in summer; check the compost daily in warm weather and water thoroughly when the top few centimetres are dry. In the ground, mulch deeply with composted bark (10 cm) in spring to conserve moisture and water during prolonged dry spells. Choose a position in moisture-retentive, humus-rich soil rather than freely draining sandy or chalky soil; hedychium grows best in rich, moisture-retentive conditions similar to cannas and dahlias.

Cold damage

Cold damage kills the top growth of all but the very hardiest hedychium species in UK winters; the tall, cane-like stems and large leaves blacken and collapse at the first hard frost in autumn. This is entirely normal and expected behaviour; hedychium regrows from the rhizomes in spring. The main concern in winter is protecting the rhizomes themselves from frost: the rhizomes of tender species such as Hedychium gardnerianum and Hedychium coccineum can be damaged or killed by frost below about -5 to -8°C, particularly in wet soil; Hedychium densiflorum rhizomes are somewhat hardier, surviving to about -10 to -15°C in well-drained, mulched conditions.

What to do

After the first hard frost kills the top growth (typically November), cut the dead stems to the ground. Apply a deep mulch of composted bark or straw (15 to 20 cm) over the entire root zone to insulate the rhizomes from further frost. In colder UK gardens, bring tender hedychium species (Hedychium gardnerianum, Hedychium coccineum) inside before the first frost: lift the rhizomes, dry off the excess compost, and store in barely moist compost in a frost-free greenhouse or conservatory for winter. Restart in spring when new growth begins.

Wind scorch

The large, thin-textured leaves of hedychium are highly susceptible to wind scorch; cold, drying winds in spring (when plants are moved outside after winter indoors) or persistent summer winds cause the leaf edges and tips to turn brown, dry out, and curl. Container-grown plants moved from a sheltered indoor position directly to a windy outdoor location often suffer severe wind scorch before they have hardened off; the contrast between indoor and outdoor conditions is too great for immediate adaptation. The damage is cosmetic rather than life-threatening but significantly reduces the plant's appearance.

What to do

Harden off container-grown hedychium gradually over 2 to 3 weeks in spring: move first to a sheltered, lightly shaded outdoor spot for a week, then to the final position; this acclimatises the leaves to outdoor wind and temperature before full exposure. Choose a sheltered position in the garden (behind a wall, fence, or large shrub) to reduce wind exposure on the large leaves. Wind scorch on already-outdoor plants is primarily cosmetic; damaged leaves cannot recover, but new leaves produced later in the season will be undamaged if the wind exposure is reduced.

Waterlogging

Hedychium needs consistently moist but aerated soil; the rhizomes rot in waterlogged, anaerobic conditions, particularly in cold, wet winters. Waterlogging is most damaging to the rhizomes in winter when they are dormant and root respiration is lowest; wet soil in winter can kill the rhizomes at temperatures well above the frost threshold. The combination of cold and wet is the most damaging winter scenario; in freely draining soil even tender hedychium species are significantly more frost-tolerant.

What to do

Ensure the planting position drains freely; avoid low-lying, poorly draining positions, particularly in winter. On heavy clay soils, improve drainage by incorporating coarse grit or grow in raised beds. In containers, ensure drainage holes are clear; do not allow pots to sit in standing water. Reduce watering substantially in winter when the plants are dormant; minimal water is needed to keep the rhizomes from desiccating completely, but the rhizomes must not sit in wet compost.

Frequently asked questions

Why are my hedychium leaves curling?

Hedychium leaves curl most commonly because of drought stress (the large, thin-textured leaves curl inward when the root zone dries out; containers dry quickly in summer), cold damage killing the top growth in frost (normal behaviour; the plant regrows from the rhizomes), wind scorch on the large leaves in cold or drying winds, or waterlogging of the rhizomes in wet winter soil. In consistently moist, sheltered conditions, hedychium is a spectacular and largely trouble-free exotic-looking UK garden plant.

Is hedychium hardy in the UK?

Hardiness varies by species. Hedychium densiflorum is the hardiest, surviving to about -10 to -15°C with deep mulching in well-drained soil; reliable outdoors in most of the UK. Hedychium gardnerianum and Hedychium coccineum are borderline hardy (to about -5 to -8°C) and best lifted or heavily mulched in colder UK gardens. All species need the rhizomes protected from frost and wet; dry, mulched rhizomes tolerate significantly lower temperatures than wet ones.

How do I grow hedychium in the UK?

Plant rhizomes horizontally 5 to 8 cm deep in spring in moisture-retentive, humus-rich, well-drained soil in a warm, sheltered, sunny position. Water regularly and mulch deeply. Feed monthly from May to August. Cut dead stems to the ground after autumn frost; apply 15 to 20 cm of bark mulch over the root zone. In colder UK gardens, lift tender species before the first frost and overwinter dry under glass.

When does hedychium flower in the UK?

Hedychium flowers from late August to October in the UK, making it one of the latest-flowering border plants; Hedychium densiflorum cultivars flower earliest (from August), while Hedychium gardnerianum and Hedychium coccineum flower in August to September. A warm summer produces more and earlier flowers. The fragrance of Hedychium gardnerianum (jasmine-like) is outstanding. In cool UK summers, some species may not flower before the first autumn frost.