Plant library · Ferns & Shade Plants
Osmundastrum cinnamomeum
Cinnamon fern is a large, native perennial for shaded ground that stays reliably moist or boggy. Its roughly 3-foot height and width give it enough presence to read as a broad-textured mass rather than a small filler. Use it where a bold green clump can anchor the middle or back of a damp shade border, with lower plants kept clear of its base.
Set cinnamon fern in rain-garden edges, pondside planting beds, damp woodland borders, or other partly shaded areas where the soil does not dry out. Group several plants to make a continuous fern drift, but keep the front edge of the planting reachable from a path for cleanup and for viewing the distinctive fertile fronds in spring. Its upright, clumping form works well behind lower shade plants and beside structures that cast filtered rather than dense, dry shade.[1][2]
Plant on 30-inch centers. Each clump can reach about 3 feet wide, so adjacent plants will knit into a nearly continuous planting as they fill their allotted space. In a mixed bed, reserve a 3-foot-wide footprint per plant and avoid crowding the crown with smaller plants that would be hidden as the fronds rise. For a looser, specimen-like arrangement, leave additional open space between clumps.
Choose partial shade and consistently wet ground. This fern suits low spots and boggy soil that can be difficult to use for plants needing ordinary drainage. Keep it out of locations that become dry beneath tree roots, roof overhangs, or densely planted shrub borders; dry soil can cause it to go dormant. Moist, humus-rich, acidic soil supports the strongest long-term display.[1][2]
Separate cinnamon-brown fertile fronds appear in early spring, standing among the emerging foliage before fading by midsummer. The larger sterile fronds carry the main summer display and turn yellow in autumn. Because the fern is deciduous, plan for an open patch in winter rather than relying on it to screen a bed edge or provide year-round cover.[1][2]
Cinnamon fern is a long-lived planting once established, but it may take time to settle into a new bed. Give each clump a permanent place instead of treating it as a temporary gap-filler. Where a bed alternates between saturation and drought, place it only in the portion that stays moist through summer, since prolonged dry soil can interrupt its seasonal display.[1]
Editorial content updated 2026-07-20.