By: Mary H. Dyer, Credentialed Garden Writer
Also known as Japanese shield fern or Japanese wood fern, autumn fern (Dryopteris erythrosora) is a hardy plant suitable for growing as far north as USDA hardiness zone 5. Autumn ferns in the garden offer beauty throughout the growing season, emerging coppery red in spring, eventually maturing to a bright, glossy, kelly green by summer. Read on to learn how to grow autumn ferns.
Like all ferns, the autumn fern produces no seeds and no flowers are required. Thus, ferns are strictly foliage plants. This ancient woodland plant thrives in partial or full shade and moist, rich, well-drained, slightly acidic soil. However, autumn fern can tolerate short periods of afternoon sunlight, but won’t perform well in intense heat or prolonged sunlight.
Is autumn fern invasive? Although autumn fern is a non-native plant, it is not known to be invasive, and growing autumn ferns in gardens couldn’t be easier.
Adding a few inches of compost, peat moss or leaf mold to the soil at planting time will improve growing conditions and get the fern off to a healthy start.
Once established, autumn fern care is minimal. Basically, just provide water as needed so the soil never becomes bone dry, but be careful not to overwater.
Although fertilizer isn’t an absolute necessity and too much will damage the plant, autumn fern benefits from a light application of slow-release fertilizer just after growth appears in spring. Keep in mind that autumn fern is a naturally slow-growing plant.
Fall is a good time to apply an inch or two (2.5-5 cm.) of compost or mulch, which will protect the roots from possible damage caused by freezing and thawing. Apply a fresh layer in spring.
Autumn fern tends to be disease resistant, although the plant may rot in soggy, poorly-drained soil. Pests are rarely a problem, with the exception of possible damage from slugs.
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Don’t over look using ferns in container gardens. One of the most versatile foliage plants, there are over 12,000 varieties of ferns. They have been around for millions of years and come in all kinds of colors, textures and sizes. Ferns can be delicate plants with lacy leaves or a broad-leafed type which grows several feet tall.
Use ferns in single planting containers on their own, or mix them with other flowers or foliage plants.
I generally like ferns in a single planting – part of their beauty is in the reach or curve of their fronds (leaves). I like to give them plenty of room in their own pot to do this. Then, I raise them up a level or two behind flowering containers to provide a backdrop for them, or I use them alone as a single container accent.
Ferns offer a dazzling array of foliage textures, structure, and color to a garden. Having adapted over eons to changing climates, they are among of the most successful plant species to have ever inhabited the earth.
Ferns can be found from coastal rain forests to alpine xeriscapes, from wetlands to serpentine soils.
So, how can there not be one perfect for your home garden?
It is good to recognize that ferns are not all the same. The fern you bought to grow as a houseplant may be better adapted to your garden. Misting it every day may not be enough, if it is used to 80 or 90 percent humidity.
On the other hand, an alpine fern is used to a drier environment and lower humidity, so you may be drowning it by watering too often. Put your garden ferns outdoors in a suitable environment. By doing a little research first, you can be sure they will thrive where you place them. (See resources in sidebar.)
If you’re looking for ground covers, the alpine water fern (Blechnum penna-marina), an evergreen with coppery red fronds, forms a dense ground cover in sunlight given a moist but well-drained soil. The western oak fern (Gymnocarpium disjunctum) and the common oak fern (G. dryopteris), both native to the peninsula, are options for consistently moist, shady areas of the garden.
As if the gorgeous shades of green weren’t enough to recommend them, some ferns come dressed in colorful foliage. Consider the eye-catching autumn fern (Dryopteris erythrosora). Its new fronds emerge orange-bronze in the spring and fade to green in the summer. In the fall, they produce bright red sori (spore sacs) on the underside of the fronds.
Ferns in the genus Athyrium transplant to the garden easily and propagate readily, making them good choices for a background drift with colorful flowering perennials. The lady fern (A. filix-femina) is a widely available hardy native example. A cultivar, A. angustum, “Lady in Red,” has brilliant ruby red spines and lime-green leaflets.
Other showy members are variants and cultivars of the Japanese painted ferns (A. niponicum) including ‘Pictum’ with silvery pinnules on deep purple blades and ‘Silver Falls’ with gracefully arching silvery fronds.
Among ferns adapted to drier habitats, the maidenhair spleenwort (Asplenium trichomanes) and the alpine water fern mentioned above will thrive in rock gardens. The spleenwort is particularly tolerant of varying conditions.
In addition, the naturally occurring dwarf forms of the western maidenhair (Adiantum aleuticum), the ‘Imbricatum’ and ‘Subpumilum’ will grow with minimal fuss in bright light and relatively dry conditions as will the dwarf western sword fern (Polystichum imbricans), which loves the sun and a rocky substrate. These dwarf forms will grow slowly and grace a retaining wall for years with little care.
The ubiquitous native sword fern (Polystichum munitum) has the attributes of a good specimen plant, with layer after layer of fronds circling a compact crown. It is a workhorse among ferns.
Its structurally upright habit can reach as high as 5 feet and sport as many as 50 fronds. It takes full sun and is remarkably drought tolerant, yet thrives in moist, shady woodland settings.
Alone or in groupings, the sword fern adds a commanding structural element to any garden. If you only have one fern in your garden, make it this one.
Here are two unusual specimens for those fortunate to have a marsh on their property. The visually striking royal fern (Osmunda regalis) and its cousin the cinnamon fern (Osmundastrum cinnamomeum) can grow as tall as 8 and 5 feet, respectively.
They thrive in moist habitats in open light or shade. The royal fern produces distinctive reddish-brown spores on the tips of specialized fronds. The dramatic appearance of cinnamon red spore-bearing spikes from the center of the cinnamon fern adds to its color and structural interest.
Ferns have few predators and will reward you despite your neglect.
Whether you are a seasoned gardener or a beginner, they are a sure bet to enhance your garden with minimal care.
Sara Farinelli is a Clallam County Master Gardener volunteer.
Dryopteris erythrosora 'Brilliance'
Brilliance Autumn Fern foliage
Brilliance Autumn Fern foliage
Other Names: Japanese Red Shield Fern
Lovely deep green fronds fiddleheads and fronds emerge copper colored great woodland and shade garden plant keep evenly moist
Brilliance Autumn Fern's attractive glossy ferny compound leaves emerge coral-pink in spring, turning forest green in color with prominent coppery-bronze tips the rest of the year. Neither the flowers nor the fruit are ornamentally significant.
Brilliance Autumn Fern is a dense herbaceous evergreen fern with a shapely form and gracefully arching fronds. It brings an extremely fine and delicate texture to the garden composition and should be used to full effect.
This is a relatively low maintenance plant, and should be cut back in late fall in preparation for winter. Deer don't particularly care for this plant and will usually leave it alone in favor of tastier treats. It has no significant negative characteristics.
Brilliance Autumn Fern is recommended for the following landscape applications
Brilliance Autumn Fern will grow to be about 18 inches tall at maturity, with a spread of 18 inches. Its foliage tends to remain dense right to the ground, not requiring facer plants in front. It grows at a medium rate, and under ideal conditions can be expected to live for approximately 15 years.
This plant does best in partial shade to shade. It is quite adaptable, prefering to grow in average to wet conditions, and will even tolerate some standing water. It is particular about its soil conditions, with a strong preference for rich, acidic soils. It is somewhat tolerant of urban pollution, and will benefit from being planted in a relatively sheltered location. Consider applying a thick mulch around the root zone over the growing season to conserve soil moisture. This is a selected variety of a species not originally from North America, and parts of it are known to be toxic to humans and animals, so care should be exercised in planting it around children and pets. It can be propagated by division however, as a cultivated variety, be aware that it may be subject to certain restrictions or prohibitions on propagation.