Plant problems

Why Are My Saccharum Leaves Curling?

Q: How do I grow saccharum ravennae in the UK?

Saccharum ravennae (Ravenna grass, plume grass) can be grown successfully in a UK garden in a warm, sheltered, sunny position with freely draining soil; it is one of the most impressive large ornamental grasses that can be attempted in the UK, but its ultimate size, marginally hardy nature, and warm-season character mean it requires care in positioning and overwintering. Position: full sun in the warmest, most sheltered available position; a south-facing wall or fence provides reflected heat that benefits the plant in marginal UK conditions; shelter from cold north and east winds through winter is important for survival. Soil: freely draining, moderately fertile soil; saccharum ravennae tolerates a range of soil types including clay, loam, and sandy soils once established but performs best on a well-drained, reasonably fertile soil that does not waterlog in winter. Size: allow for a very large plant; mature clumps can reach 2 to 4 m in height including the plumes and 1.5 to 2 m in spread; this is a back-of-border or specimen plant for a large garden, not a small border plant. Plumes: the primary ornamental feature; large (60 to 90 cm), feathery, silvery-white plumes produced from late August through October in good conditions; the plumes are similar in character to pampas grass (Cortaderia selloana) plumes but more open, loosely branching, and feathery; they persist into winter and are spectacular backlit in autumn and early winter sunlight. Overwintering: in the south of England, established plants typically survive UK winters without protection, dying back to the ground and resprouting in late spring (May to June); in the colder parts of the UK and in particularly cold or wet winters, mulch the crown heavily with a thick dry mulch in late autumn to insulate against frost; in northern England and Scotland, the species is best treated as a tender perennial and overwintered in a frost-free greenhouse or brought indoors.

Q: What is the difference between saccharum ravennae and cortaderia selloana?

Saccharum ravennae (Ravenna grass, plume grass) and Cortaderia selloana (pampas grass) are both large, spectacular ornamental grasses grown in UK gardens for their dramatic late-season plumes, but they differ in a number of important characteristics: Plumes: Cortaderia selloana plumes are typically white or pink, dense, and feather-duster-like, with a compact, bushy, heavily plumed silhouette; Saccharum ravennae plumes are more open, loosely branching, and feathery, silvery-white to beige, with a more airy, transparent quality that catches the light differently, particularly when backlit in autumn; the ravenna grass plume is often described as more elegant and less theatrical than the pampas grass plume. Size and habit: both species are large, but Cortaderia selloana tends to have a more compact, dense, rounded mound of leaves with the plumes held vertically above; Saccharum ravennae is slightly more upright in its leaf character, with the leaves arranged more loosely and the stems taller and more maize-like. Hardiness: Cortaderia selloana is broadly hardy across the UK in most winters with no special protection; Saccharum ravennae is marginally hardy in the south of England, dying back to the ground in most winters but resprouting in late spring; in northern England and Scotland it requires winter protection. Flowering season: both species flower in late summer and autumn (August to October); the timing is similar but both are effective from late August onwards. Leaf character: Cortaderia selloana has narrower, more firmly rolled, glaucous blue-grey leaves with very sharply serrated edges (dangerous to handle); Saccharum ravennae has broader, flatter, more maize-like leaves with a less sharply serrated edge. In a garden where both would thrive, Saccharum ravennae provides a somewhat different aesthetic character from pampas grass and is less commonly planted, making it more distinctive as a specimen.

Q: Can sugar cane (saccharum officinarum) be grown in the UK?

Saccharum officinarum (sugar cane) can be grown in the UK as a tender annual or short-lived perennial in a heated greenhouse or conservatory, or outdoors as a summer annual in a warm, sheltered position in the warmest parts of southern England, but it is not frost-hardy and cannot survive UK winters outdoors. As a tropical grass of equatorial and subtropical origin, sugar cane requires temperatures consistently above 20°C for active growth and above 15°C to avoid cold damage; the UK outdoor growing season is generally too short and too cool for it to reach its full ornamental size (it can reach 3 to 5 m in its tropical homeland) but it grows sufficiently to produce an impressive, dramatic, maize-like plant in a warm, sheltered UK summer. In a UK conservatory or heated greenhouse maintained at above 15°C year-round, sugar cane can be grown as a permanent specimen for its dramatic tropical foliage; some cultivars (notably 'Pele's Smoke', with very dark purple-black stems and leaves) are particularly striking as indoor or conservatory foliage plants. Sugar cane is commercially grown as a major global crop in tropical and subtropical regions of South and Central America, the Caribbean, South and Southeast Asia, and Australia for the production of sucrose from the stem juice; it is the world's most produced crop by tonnage. Some specialist UK tropical plant nurseries offer ornamental cultivars of Saccharum officinarum, including coloured and striped-leaf forms, as novelty or specimen conservatory plants; these are grown for foliage effect rather than sugar production and are interesting additions to a tropical-themed UK conservatory or garden scheme in a warm, sheltered position in summer.

Saccharum ravennae (Ravenna grass) is one of the tallest ornamental grasses that can be attempted in a UK garden, producing spectacular open, feathery, silvery-white plumes in late summer. A marginally hardy warm-season grass; leaves curl and brown from cold temperatures, insufficient summer heat to fully develop the plumes, or drought and poor drainage. Warmest possible sheltered position is essential in the UK.

Cold damage and autumn die-back

Saccharum ravennae is a warm-season C4 grass marginally hardy in the UK; as temperatures drop in September and October, the large maize-like leaves curl, brown, and die back. The growing point at the base typically survives UK winters in the south unless the winter is extremely cold or prolonged. Saccharum officinarum (sugar cane) is fully tropical, killed by any frost, and cannot survive UK winters outdoors.

What to do

In southern England, established plants typically survive without protection, dying back and resprouting in late spring (May to June); mulch the crown heavily with a thick dry mulch in late autumn as insurance in cold spells. In northern England and Scotland, treat as a tender perennial and overwinter in a frost-free greenhouse or bring container-grown plants indoors. Cut back dead top growth in spring once the risk of hard frost has passed and new growth emerges from the base.

Insufficient summer heat

A warm-season C4 grass requiring a long, warm growing season to fully develop the spectacular feathery plumes (up to 60 to 90 cm long) that are its primary ornamental feature. In a cool, short UK summer, the plumes may be delayed, smaller, or absent; the leaves curl in from the margins and the tips brown in cool conditions below the plant's active growth temperature. The warmest UK summers in sheltered, south-facing positions give the most reliable plume production.

What to do

Position in the warmest, most sheltered available spot; a south-facing wall or fence provides reflected heat that extends the effective growing season. In a warm UK summer the plumes are produced from August and persist through October and into early winter; in a cool summer they may be smaller or delayed. Avoid growing in a cool, exposed, north-facing position; the UK climate is at the marginal northern edge of reliable plume production for this species.

Drought and poor drainage

Drought-tolerant once established but young or container-grown plants show leaf curl and tip browning in extended dry spells. Conversely, poor drainage in a heavy, waterlogged UK soil damages roots and leads to paradoxical drought-like leaf symptoms. The combination of warm sun and freely draining, moderately fertile soil gives the best results; waterlogged winter conditions are more damaging to the crown than frost alone.

What to do

Plant in freely draining, moderately fertile soil; on a heavy clay soil, incorporate significant quantities of horticultural grit before planting and avoid low-lying areas that waterlog in winter. Water regularly in the first growing season to establish the root system; once established, water only in prolonged severe drought. In winter, ensure the crown does not sit in cold, standing water; this is the most damaging winter condition for saccharum ravennae in a UK garden.

Frequently asked questions

Why are my saccharum leaves curling?

Saccharum leaves curl most commonly because of cold damage and autumn die-back (marginally hardy warm-season grass; leaves curl, brown, and die back as temperatures drop in September to October; growing point at the base typically survives in southern England; heavy dry mulch on crown in late autumn; cut back dead growth in spring when new growth emerges from the base), insufficient summer heat (C4 warm-season grass needing a long, warm season for full plume development; plumes may be delayed, smaller, or absent in cool UK summers; warmest available sheltered south-facing position), or drought and poor drainage (young plants curl in dry spells; waterlogged winter soil damages roots; freely draining, moderately fertile soil; avoid low-lying areas that waterlog in winter). Warmest sheltered position is the key requirement.

How do I grow saccharum ravennae in the UK?

Full sun in the warmest, most sheltered position; a south-facing wall or fence provides reflected heat. Freely draining, moderately fertile soil; tolerates clay, loam, and sandy soils once established; avoid waterlogging in winter. Allow for a very large plant (2 to 4 m height including plumes, 1.5 to 2 m spread); back-of-border or specimen plant for a large garden. Plumes (60 to 90 cm) produced from late August through October; open, feathery, silvery-white, spectacular backlit in autumn sun. Established plants in southern England survive most UK winters without protection; mulch crown heavily in very cold spells; cut back dead growth in spring when new basal growth appears.

What is the difference between saccharum ravennae and cortaderia selloana?

Plumes: Cortaderia selloana plumes are dense, bushy, compact, white or pink (feather-duster-like); Saccharum ravennae plumes are more open, loosely branching, feathery, silvery-white to beige (more airy and transparent; particularly spectacular backlit). Hardiness: Cortaderia is broadly hardy across the UK; Saccharum ravennae is marginally hardy in the south, requires protection in the north. Leaf: Cortaderia has narrow, tightly rolled, blue-grey, very sharply serrated leaves (dangerous to handle); Saccharum ravennae has broader, flatter, more maize-like leaves with less sharply serrated edges. Both flower from late August to October. Saccharum ravennae is less commonly planted, making it more distinctive as a specimen.

Can sugar cane (saccharum officinarum) be grown in the UK?

As a tender annual or short-lived perennial in a heated greenhouse or conservatory maintained above 15°C year-round; not frost-hardy, cannot survive UK winters outdoors. In very warm sheltered positions in southern England, can be grown outdoors as a summer annual; too short a growing season to reach full height (3 to 5 m in tropical homeland). Some ornamental cultivars (notably 'Pele's Smoke', with dark purple-black stems and leaves) are striking conservatory foliage plants. The world's most produced crop by tonnage; grown commercially in tropical and subtropical regions of South and Central America, the Caribbean, South and Southeast Asia, and Australia for sucrose production.