Award-winning Dryopteris erythrosora is an herbaceous perennial fern noted for the coppery-red and green triangular bi-pinnate fronds. Although the fronds turn solid green as summer progresses, a steady supply of new fronds renders the plants a visual tapestry of dark green interwoven with pink to bronzy tones. At maturity, the fronds arch from the center of the clump to form a graceful vase shape. Autumn fern is evergreen in frost-free areas and is semi-evergreen to deciduous in other areas depending on the severity of winter temperatures.
For best growth, give autumn fern a rich, highly organic, moist but well drained, acid soil. While autumn fern is becoming established, keep it evenly moist. After it is well established, it becomes more drought tolerant and performs satisfactorily in the dry shade beneath large trees. The foliage changes color when it becomes water-stressed, signaling to the observant gardener that it needs a drink. Like most ferns, autumn fern does best in full to partial shade.
Plant about 18 inches apart for complete ground coverage. Keep your autumn fern growing at a steady pace by applying a balanced fertilizer at the rate of one pound per 100 square feet in spring before new growth begins. Keep it well watered until it is thoroughly established, and then back off. Remove dead fronds each spring to keep the planting looking neat. Pests and diseases rarely bother autumn fern.Clumps of autumn fern increase in diameter very slowly since the rhizomes are short. Propagation is easily accomplished by division of mature clumps.
The cultivar ‘Brilliance' has more brilliant reddish to coppery coloring than the species and holds much of its coloration when it becomes mature. The variety called Dryopteris erythrosora var. purpurascens (syn. Dryopteris purpurella) has fronds that reach three feet tall or more, so it is significantly larger. Bright cinnamon-red fronds emerge in spring and early summer. Dryopteris erythrosora var. prolifica is a form with very narrow leaf parts (pinnules). It produces bulblets on the edges of the pinnules and has a rather floppy growing habit.
Landscape Uses Autumn fern is most at home in shaded woodland gardens where it is allowed to make a solid mass, but it also holds its own in selected areas as an accent plant. Frequently it is used as a backdrop for flowering shade plants. Sometimes it is chosen as a foundation plant in a shady spot, and it is equally effective grown in a container on a shaded patio.
The scientific name of this fern describes its preferred growing site as well as one of its physical characteristics. Dryopteris is from the Greek words drys (tree) and pteris (fern), referring to its preferred spot under the shade of a tree. Erythrosora is from the Greek words erythros (red) and sora (sori) in reference to its red sori.
At a Glance:
Scientific name: Dryopteris erythrosora (dry-OP-ter-ris air-rith-roh-SOR-ruh)
Other names: Copper shield fern, shaggy shield fern, Japanese red shield fern, Japanese wood fern
Origin: Japan, China, Korea, Taiwan
Hardiness: USDA Zones 5-9
Light: Shade to part (morning or dappled) sun
Water use zone: Moderate after establishment
Size: 18 to 24 inches tall and wide
Soil: Moist (until well established), humus rich, well-drained, slightly acid
Salt Tolerance: Slight
Pictures are by the author except for the close-up of colored leaves by Kniphofia and the unfurling crozier or fiddlehead by htop. Thank you, kniphofia and htop.