Asplenium ceterach
rustyback
western and southern Europe, North Africa, and western Asia
Overview
Asplenium ceterach is a small evergreen fern that grows in rock crevices and old mortared walls, forming tufts of fronds 3-20 cm (1-8 in) long. The fronds are deeply lobed rather than fully divided, with rounded segments set alternately along the midrib, leathery and dark green above. The undersides are densely covered with overlapping scales that start silvery and age to rust-brown, the feature behind the common name rustyback. In dry spells the fronds curl inward to expose the scaly undersides and turn greyish, then unfurl and green up within hours of rain, which lets the plant survive drought on exposed stone. It spreads slowly by spores that settle in lime-rich cracks, and clumps stay small and tight. Roots anchor in very little soil, drawing moisture from the rock itself. The plant fails in rich, wet ground and rots where drainage is poor, so it is confined to walls, tufa, and gritty alkaline pockets rather than open borders.
Native Range
Asplenium ceterach is native to western and southern Europe, North Africa, and western Asia, where it grows on limestone outcrops, cliffs, and old walls. It is most common in regions with mild, wet winters and dry summers.Suggested Uses
Grown in crevices of dry-stone and mortared walls, in alkaline rock gardens, and in tufa or trough plantings. It suits gritty, lime-rich spots that stay dry in summer. Its need for sharp drainage and lime rules it out of conventional borders.How to Identify
Appearance
Size & Dimensions
Height1" - 8"
Width/Spread3" - 8"
Bloom Information
As a fern, Asplenium ceterach produces no flowers. It reproduces by spores borne in linear sori along the veins on the frond undersides, ripening from summer into autumn (June to October). The spore patches are partly hidden by the dense scales.
Detailed Descriptions
Foliage Description
dark green with rust-brown scales beneathGrowing Conditions
Sun Requirements
Requires 3-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Asplenium ceterach grows in full sun to part shade on sharply drained, lime-rich substrates such as mortar, tufa, and limestone grit. It needs very little soil and tolerates drought by curling its fronds until moisture returns. Watering is occasional, since constant moisture and rich soil cause the roots to rot. A pH on the alkaline side, roughly 7.0 to 8.0, suits it. It establishes slowly from spores or by wedging divisions into damp crevices. No feeding is needed and disturbance is poorly tolerated.Pruning
Dead or frost-damaged fronds are trimmed off at the base in spring as new growth appears. No other pruning is required. The plant is left undisturbed because it re-establishes slowly.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
early spring
Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons