Plant problems

Why Are My Fascicularia Leaves Curling?

Q: Why are my fascicularia leaves curling?

Fascicularia (Chilean bromeliad) leaves curl and brown most commonly in UK gardens because of cold damage in hard UK winters (fascicularia bicolor, the only widely grown species in the UK, is generally hardy to approximately -8 to -10°C in very sheltered, freely draining conditions, but the spiky, bromeliad-like rosette leaves curl, brown, and collapse after sustained frost below about -5°C; the inner leaves and growing point at the centre of the rosette are harder than the outer leaves), waterlogging in poorly draining soil (fascicularia comes from rocky, freely draining cliff and coastal scrub habitats in Chile and cannot tolerate saturated conditions; the roots rot in wet, heavy soil), or drought stress (the narrow, spiky leaves curl and grey at the tips when the rosette dries out excessively; the central tank of the rosette needs to contain some water at all times in the growing season). Fascicularia bicolor is a stemless or short-stemmed, bromeliad-family (Bromeliaceae) perennial from rocky, coastal, and cliff habitats in Chile; it is the only member of the bromeliad family that is genuinely hardy in the UK. It produces tight rosettes of narrow, recurving, grey-green, spine-edged leaves similar to a terrestrial bromeliad; in summer (July to August) the central leaves of the rosette turn a brilliant scarlet-red as the plant prepares to flower, producing a cluster of blue-lilac flowers at the rosette centre. This dramatic colour change from grey-green to scarlet is the principal ornamental event of the plant's year.

Q: Is fascicularia hardy in the UK?

Fascicularia bicolor is generally considered to be one of the hardiest members of the bromeliad family (Bromeliaceae) available to UK gardeners; it is reliably perennial in the very mildest UK areas (coastal south and west England, Wales, and Ireland, sheltered urban gardens in the south-east) where frosts rarely fall below -5 to -6°C. In harder UK winters it is less reliable; the outer leaves may be damaged or killed by frost while the inner growing point survives, or the entire rosette may be killed in a very hard frost combined with wet. In practice, fascicularia is most reliably grown in the UK in one of three ways: as an outdoor plant in the very mildest areas with fleece protection in cold snaps; as a container plant that is brought into a cool greenhouse or conservatory from October to April; or in an unheated, dry greenhouse year-round where it thrives with maximum light and minimal winter moisture. Some UK gardeners in the warmest, most sheltered gardens have grown fascicularia outdoors for many years with reliable success; others find it an unpredictable overwintering subject that needs to be treated as tender. The key variables are soil drainage (freely draining soil dramatically improves cold tolerance), shelter (a south-facing wall or the shelter of a larger plant significantly reduces frost damage), and winter moisture (dry, cold conditions are much more survivable than cold combined with wet).

Q: How do I grow fascicularia in the UK?

Fascicularia grows best in a very sheltered, sunny position in freely draining, sandy or gritty, low-fertility soil; a south-facing wall base, rock garden, raised bed, or gravel garden in the warmest UK microclimate available is ideal. The plants come from rocky, coastal, and cliff habitats in Chile where the soil is thin, freely draining, and low in fertility; rich, heavy, or moist soils promote soft, lush growth that is more susceptible to frost damage and disease. Incorporate generous quantities of coarse grit (50% by volume) into heavy soils before planting; apply a coarse gravel or grit mulch around the base to keep the crown dry and reduce frost penetration. Keep water out of the rosette in winter; the central tank that holds water naturally (like most bromeliads) can freeze in hard frosts, expanding the ice and damaging the growing point. This is one reason why overwintering in a dry greenhouse or cold frame is the most reliable approach in most of the UK. In summer, allow the natural rainfall to fill the rosette tank; this is normal and beneficial. Apply a very dilute liquid fertiliser once a month from May to August poured into the rosette tank and around the base; do not over-feed. In milder areas, protect from frost from October to April with several layers of fleece whenever frost is forecast; remove fleece on milder days to prevent condensation.

Q: Why does fascicularia turn red?

The scarlet or crimson colouration of the inner leaves of fascicularia in summer is a natural and highly ornamental phenomenon associated with flowering; the central leaves of the rosette turn brilliant red or scarlet in July to August as the plant prepares to produce its cluster of blue-lilac flowers at the rosette centre. This colour change is triggered by the approach of the flowering period and is a mechanism for attracting pollinators to the otherwise inconspicuous blue flowers hidden within the rosette; the red leaves act as a visual signal to hummingbirds and insects in the plant's native Chile. In UK gardens without hummingbirds, the flowering still triggers the scarlet colour change, which is the most dramatic ornamental feature of the plant and one of the reasons fascicularia is prized despite its relatively demanding cultivation requirements. After flowering, the colour of the central leaves gradually fades back toward the grey-green of the outer leaves; the flowering rosette then produces offsets from the base that will become the next generation of flowering rosettes. The central rosette itself does not die after flowering (fascicularia is not strictly monocarpic in the manner of agave), though the flowering rosette may decline somewhat while the offsets take over as the dominant growing points. The red colouration does not indicate stress or disease; if the outer leaves (rather than the inner leaves) are turning red or brown, this is more likely to be frost damage or drought stress.

Fascicularia bicolor (Chilean bromeliad) is the only genuinely hardy bromeliad available to UK gardeners: a tight, spiky, grey-green rosette of narrow, recurving, spine-edged leaves that turns a spectacular scarlet at the centre in July to August when the blue-lilac flowers appear. Borderline hardy in most UK gardens, it is most reliable in the very mildest areas or in a container brought under cover for winter.

Cold damage

Cold damage is the most common cause of fascicularia leaf curl and browning in UK gardens; the outer rosette leaves curl, brown, and collapse after frost below about -5°C, while the inner growing point may survive. Water freezing in the central rosette tank in hard frosts expands and damages the growing point directly. In a severe UK winter, the entire rosette may be killed; in a mild winter, only the outermost leaves are damaged and the plant continues to grow and flower normally.

What to do

In mild UK areas, wrap the rosette in two to three layers of horticultural fleece when frost is forecast; a south-facing wall position dramatically reduces exposure. Crucially, tip the rosette sideways before hard frost to empty the central tank; this prevents ice damage to the growing point. In colder areas, grow in a container and bring into a frost-free cool greenhouse or conservatory from October to April. Remove brown outer leaves in spring once new growth confirms survival.

Waterlogging

Fascicularia comes from rocky, freely draining cliff and coastal scrub habitats in Chile and cannot tolerate waterlogged, saturated soil; the roots rot rapidly in persistently wet conditions, causing the leaves to yellow, curl, and the rosette to collapse. Cold wet conditions from October to March are particularly lethal. Heavy clay soils and low-lying garden positions are the most dangerous environments for outdoor fascicularia in the UK.

What to do

Plant only in freely draining conditions; incorporate 50% coarse grit in heavy soils or grow in a raised bed with a lean, gritty growing medium. Apply a coarse gravel collar around the base to keep the crown dry. Avoid overhead watering in winter; in wet UK autumns, a sheet of glass or polycarbonate propped over the plant reduces excess rainfall around the crown. In containers, use a very freely draining mix and ensure drainage holes are clear.

Drought stress

Although fascicularia is from a relatively dry habitat, the central rosette tank is designed to collect and hold rainwater; the plant uses this reservoir for moisture between rainfall events. When the rosette is dry for extended periods in summer, the narrow leaves curl and grey at the tips. Container-grown fascicularia and plants in very freely draining, sandy soils are most at risk during hot UK summers. The drought response is reversible; normal appearance returns when rainfall refills the rosette tank.

What to do

During dry spells in summer, water directly into the rosette centre to refill the tank as well as around the base. Once or twice a month from May to August, add a very dilute liquid fertiliser to the tank water. Do not over-water in winter; the rosette tank should be kept dry through winter to prevent ice damage and crown rot.

Frequently asked questions

Why are my fascicularia leaves curling?

Fascicularia leaves curl most commonly because of cold damage (outer leaves curl and brown below -5°C; tip the rosette to empty the tank before hard frosts to prevent ice damage to the growing point; fleece or greenhouse protection), waterlogging (roots rot in saturated soil; plant in perfectly draining, gritty conditions; raised bed or rock garden), or drought stress in summer (the rosette tank dries out; water into the tank during dry spells; recovers when rainfall returns). Cold combined with wet is the most lethal UK condition.

Is fascicularia hardy in the UK?

Fascicularia bicolor is the hardiest bromeliad available to UK gardeners, tolerating approximately -8 to -10°C in very sheltered, freely draining conditions; it is reliably perennial only in the mildest UK areas (coastal south and west, sheltered urban gardens). In most UK gardens it is more reliable in a container brought under cover from October to April. The critical factors are: soil drainage (freely draining), shelter (south-facing wall), and keeping the rosette tank dry and empty in winter to prevent ice damage.

How do I grow fascicularia in the UK?

Grow in the warmest, most sheltered available position in full sun in very freely draining, lean, gritty soil; a south-facing wall, rock garden, or raised bed with 50% coarse grit is ideal. Apply a gravel crown collar; keep the rosette tank dry and empty from October to April (tip the rosette or cover it to prevent rain filling it in winter). In summer, allow rainfall to fill the tank and feed monthly with a very dilute liquid fertiliser poured into the tank. Bring under cover in colder areas.

Why does fascicularia turn red?

The brilliant scarlet colouration of the inner leaves in July to August is a natural, ornamental phenomenon triggered by flowering; the central leaves turn red to attract pollinators (hummingbirds in its native Chile) to the blue-lilac flowers hidden in the rosette centre. This colour change is the principal ornamental event of the year and is not a sign of stress or disease. After flowering, the colour fades and offsets develop from the base to form the next generation of flowering rosettes.