Plant problems

Why Are My Berberidopsis Leaves Curling?

Q: Why are my berberidopsis leaves curling?

Berberidopsis corallina (coral plant or Chilean barberry) leaves curl and yellow most commonly in UK gardens because of drought stress (berberidopsis comes from cool, moist, acid forest and has no drought tolerance; the large, heart-shaped, spine-margined, glossy leaves curl inward when the root zone dries out), alkaline or chalky soil (berberidopsis is an acid-soil plant and cannot tolerate alkaline conditions; the leaves yellow from lime-induced chlorosis and progressively curl and drop), or excessive sun and heat (berberidopsis dislikes direct hot sun; it needs a shaded or semi-shaded position and wilts visibly in hot, sunny conditions). Berberidopsis corallina is a magnificent but demanding and rarely seen evergreen climbing shrub from the cool, moist coastal forests of Chile; it is grown in UK gardens as a wall climber or support-trained shrub for its large, dark green, holly-like leaves and its pendant, globular, deep crimson-red flowers produced in clusters in late summer (July to August). The combination of large, sculptural, spine-margined foliage and the deep red pendant flower clusters makes it one of the most distinctive and architecturally striking of all cool-temperate climbing plants. Berberidopsis is the sole species in its genus and is classified in its own family (Berberidopsidaceae); it is a botanical curiosity as well as an ornamental rarity and is considered endangered in its native Chilean coastal forests due to habitat loss. In UK gardens it is most reliably grown in the mildest, moistest western gardens where conditions most closely approximate its native cool, moist forest environment.

Q: Is berberidopsis hardy in the UK?

Berberidopsis corallina is moderately hardy in the UK; it is generally considered hardy to approximately -8 to -10°C in a sheltered position against a wall or in a protected woodland garden, and is reliably perennial in the mildest UK gardens (sheltered positions in south-west England, western Scotland, Wales, and mild urban gardens). In colder or more exposed UK positions, the plant is less reliable and may be damaged or killed in hard winters. Like desfontainia and mitraria, berberidopsis is considerably easier to grow in the wetter, milder western parts of the UK than in the drier, warmer south-east; the combination of cool, moist air, naturally acid soil, and mild winters in gardens such as Crarae, Logan, and Caerhays provides near-ideal conditions that simply cannot be replicated in an exposed Midlands garden. The plant is hardiest in consistently moist, acid conditions; drought-stressed or alkaline-soil-weakened plants are far less cold-tolerant than healthy, well-grown specimens in ideal conditions. A shaded north or west-facing wall in acid, moist, humus-rich soil is the most reliable UK outdoor position; in very cold areas, the plant can be grown in a large container of ericaceous compost and brought under glass in winter, though it is large and awkward to move when mature.

Q: How do I grow berberidopsis in the UK?

Berberidopsis corallina grows best in a sheltered, shaded or semi-shaded position in consistently moist, acid (pH 4.5 to 6.0), humus-rich, freely draining soil; a north or west-facing wall in lightly shaded conditions, or a position within a woodland garden that provides overhead shelter and filtered light, are the ideal UK positions. The plant climbs by twining its stems through a support; provide wires, trellis, or a framework of branches at intervals of 15 to 20 cm and train the young stems in to encourage coverage. The large, holly-like leaves and the pendant flower clusters are both most effectively displayed against a dark background (such as a shaded wall in dark stone or brick) where the deep crimson flowers and glossy foliage show to best effect. Enrich the soil generously with leaf mould, composted bark, and ericaceous compost; maintain the acid pH with annual mulching. Water with rainwater in hard-water areas; do not allow the soil to dry out at any point during the growing season. The plant is slow to establish; allow two to three years before it begins to grow away strongly. Prune minimally; remove any dead or damaged growth in spring and trim back any overcrowded shoots that are covering the plant's display. The flowers are produced on the current year's growth; some new season's vigour is therefore needed for a good flower display.

Q: Why is my berberidopsis not flowering?

Berberidopsis flowers in July to August on the current year's new growth; the pendant, globular, deep crimson flower clusters hang from the current season's shoots in late summer. Poor or absent flowering is most commonly caused by alkaline soil (weakens the plant and suppresses flower production; acid conditions are essential), drought stress (water stress during spring and early summer reduces new growth and therefore the number of flowering shoots produced), too much shade (deep shade suppresses flowering, though some shade is beneficial; the plant needs lightly dappled or bright indirect light for best flowering), or the plant being too young or recently planted (berberidopsis establishes slowly; allow two to three years for it to build up sufficient mature growth for a reliable and abundant flower display). In the right conditions, the pendant deep red flowers are among the most striking of any late-summer climbing plant in UK gardens; they hang in clusters at the ends of the current season's shoots against a backdrop of large, dark green, glossy, spine-margined leaves, creating an effect of great botanical drama that is reminiscent of the Valdivian forest environment from which the plant originates. Berberidopsis is rare in UK cultivation even today; a well-grown specimen in a UK garden is a remarkable and unusual sight.

Berberidopsis corallina (coral plant) is a rare and magnificent evergreen climbing shrub from the cool, moist coastal forests of Chile, grown for its large holly-like leaves and pendant deep crimson flower clusters in July to August. One of the most architecturally striking of all cool-temperate climbers, it demands cool, moist, acid conditions and sheltered shade. Drought stress and alkaline soil are the most common causes of decline; western UK gardens with naturally acid soil suit it best.

Drought stress

Drought stress curls and wilts the large, holly-like leaves of berberidopsis rapidly; the plant has no drought adaptation whatsoever and comes from one of the wettest forest environments in the southern hemisphere. The root zone must remain consistently moist throughout the growing season. Brief drying out causes visible leaf curl and stress; prolonged drought causes leaf drop and may kill established plants. The problem is most severe in warm, sunny, dry conditions that maximise evapotranspiration from the large leaf surface.

What to do

Maintain consistent moisture at the root; mulch deeply (10 to 15 cm) with leaf mould or composted bark; water with rainwater in hard-water areas. Position in shade or semi-shade where the microclimate is cooler and moisture is better retained; a north or west-facing wall base in deep, humus-rich soil retains moisture far better than a sunny, exposed position. Drip irrigation set on a timer is highly effective for maintaining the constant moisture berberidopsis requires.

Alkaline soil

Alkaline soil causes lime-induced chlorosis in berberidopsis; the large leaves yellow between the veins, curl, and eventually drop as the plant becomes progressively unable to extract iron and other micronutrients from high-pH soil. This is the most common cause of failure when berberidopsis is planted in gardens with chalky or alkaline soil. The problem is permanent and progressive; the plant cannot thrive in alkaline conditions regardless of how it is treated with supplements or foliar feeds.

What to do

Test soil pH before planting; acid conditions (pH 4.5 to 6.0) are essential. In alkaline gardens, construct a large raised bed (minimum 60 cm deep) filled entirely with ericaceous compost, leaf mould, and coarse grit; water with rainwater only. Annual mulching with composted bark or pine needles maintains acidity over time. A sequestered iron feed provides temporary relief from chlorosis symptoms while longer-term soil acidification is achieved.

Hot sun and heat

Berberidopsis is damaged by hot, direct sun; in a sunny, exposed position the large leaves scorch, curl, and lose their characteristic dark gloss. The plant is from cool, shaded coastal forest environments and has no adaptation to high light intensity or heat; the large leaf area both captures too much solar radiation and loses moisture rapidly through transpiration in hot, sunny conditions. A shaded or semi-shaded north or west-facing position is essential for success in warmer parts of the UK.

What to do

Position in shade or dappled shade; a north or west-facing wall that receives no direct afternoon sun is ideal in most of the UK. In western Scotland and similar cool, overcast climates, a more open position may be tolerated. The deep red flowers are actually displayed to great advantage against a dark, shaded wall where the colour intensity is maximised by the lower light levels; shade is an asset for display as well as for plant health.

Frequently asked questions

Why are my berberidopsis leaves curling?

Berberidopsis leaves curl most commonly because of drought stress (the plant needs constant moisture; no drought tolerance whatsoever; mulch deeply and water consistently with rainwater), alkaline soil (lime-induced chlorosis causes yellowing and curl; acid conditions pH 4.5 to 6.0 are essential; ericaceous raised beds in alkaline gardens), or hot, direct sun (the large leaves scorch and curl; shade or semi-shade is needed; north or west-facing sheltered position). Consistent moisture in acid, shaded conditions is the key to success.

Is berberidopsis hardy in the UK?

Berberidopsis is hardy to about -8 to -10°C in a sheltered, moist, acid position and is reliably perennial in mild western UK gardens (south-west England, western Scotland, Wales). In colder or drier parts of the UK it is more marginal; drought-stressed or weakened plants are significantly less cold-tolerant than healthy specimens in ideal conditions. Western and coastal UK gardens with naturally acid soil and mild, wet winters are the most reliable outdoor sites.

How do I grow berberidopsis in the UK?

Grow on a sheltered north or west-facing wall in shade or dappled shade, in consistently moist, acid (pH 4.5 to 6.0), humus-rich soil. Provide wires or trellis for the twining stems. Mulch annually with leaf mould; water with rainwater; enrich the soil generously with ericaceous compost. The plant is slow to establish; allow two to three years. Prune minimally: only remove dead or damaged growth in spring.

Why is my berberidopsis not flowering?

Common causes: alkaline soil (weakens the plant; acid conditions are needed); drought stress (reduces new growth and therefore the number of flowering shoots); deep shade (some shade is beneficial; dense shade suppresses flowering); or the plant being too young (allow two to three years for a reliable display). The pendant deep red flower clusters in July to August on a mature, well-grown plant in ideal conditions are among the most distinctive late-summer displays of any climbing shrub in UK gardens.