Athyrium niponicum [uh-THEE-ree-um, nip-ON-ih-kum] is often cultivated for ground cover, producing large tufts of fronds.
Native to eastern Asia, people commonly call the plant Oriental lady fern, or Japanese painted fern.
It’s part of the Athyriaceae family of fern plants.
Athyrium niponicum is easily cultivated in a variety of growing conditions.
The commonly cultivated fern also includes several cultivars and hybrids, including:
The leaves of these varieties have varying shades of green with red or purple veins.
Japanese Painted Fern Care
Size and Growth
- Athyrium niponicum grows from an underground rhizome, producing a clump of fronds growing in arches from the root system.
- It grows at a medium rate and may take several years to reach its full size.
- The fronds are triangular-shaped and typically reach about 18″ inches tall and 20″ inches across.
- The triangular, variegated fronds are grayish-green with silvery hues.
- The midribs are dark maroon.
- It sheds its leaves each year.
- During the summer, the warmer temperatures cause the grayish-green fronds to become a brighter green.
Flowering and Fragrance
Japanese painted fern is a nonflowering plant.
Light and Temperature
Japanese painted fern doesn’t require a lot of light. It thrives in partial shade to full shade.
When grown outdoors, place under the shade of other plants.
The plant can tolerate full sun, which increases the brightness of the fronds.
Unfortunately, too much sunlight also increases the risk of leaf scorching and causes the fronds to grow upward.
Athyrium niponicum grows well in a variety of environments.
It’s suited for outdoor growth in USDA hardiness zones 3 to 8, which covers most of the United States.
Watering and Feeding
- Keep the soil slightly moist during the warmer months.
- It should not dry out.
- Water plants early in the day, giving them plenty of time to soak up the moisture.
- NOTE: Excess moisture may lead to rust.
- While the soil should remain moist, it shouldn’t become soggy.
- Start adding liquid fertilizer to the water once per month at the beginning of spring.
- Stop using fertilizer at the end of summer.
Soil and Transplanting
Japanese painted fern grows easily in rich soil with good drainage.
Improve poor soil by adding lots of organic matter.
Leaf mold, animal manure, compost, and other decaying plant material provides the soil with more nutrients.
Organic matter may also improve the drainage and water retention of clay soil.
At the start of spring, divide the clumps to control the spread of the roots.
Potted plants also benefit from transplanting every two or three years.
The plant shouldn’t need pruning.
The leaves fall off at the end of the season and reappear in the spring.
How to Propagate Athyrium Niponicum
Propagate by division or cuttings.
Divide clumps of mature plants into three to four divisions during the spring.
- Dig up the soil around the plant and carefully remove the entire root system.
- Shake the soil loose and locate the center of the root ball.
- Use gardening shears to cut the root at the base, dividing it into multiple sections.
- Large clumps may be planted directly into the ground, while smaller clumps should be placed in pots.
To propagate using cuttings, cut one or more fronds from a mature plant.
- The frond should measure at least 5″ or 6″ inches.
- Stick the end of the frond in rich, well-drained soil.
- Use small pots for the cuttings and place indoors in a shaded spot, receiving filtered sunlight.
- Keep the soil moist and allow the plant to overwinter indoors.
- In the spring, transplant small divided clumps or young plants from cuttings.
- Move them outdoors to their permanent spots in the garden or larger containers.
Athyrium Niponicum Pest or Disease Problems
Slugs, snails, and caterpillars may damage the foliage. These pests feed on the leaves.
Remove the pests by hand or protect the plant by creating a protective barrier.
Add mulch or rock around the base of the plant.
Keeping the garden clean and free of plant debris also discourages pest infestations.
Japanese painted fern may also suffer from rust.
The undersides of the leaves may develop bright orange or brown growth.
Rust is often caused by moist conditions.
Amend the soil with sand to increase drainage and decrease water retention.
Move potted plants to a brighter location.
Another potential problem is the aggressiveness of the roots.
While it’s not listed as an invasive species, the plant produces a dense mat of roots, making it difficult to remove.
Suggested Japanese Painted Fern Uses
Japanese painted fern is often grown in shaded gardens or near ponds and streams with shade from other plants.
The compact growth of the plant also works well as a border.
When growing near other plants, keep an eye on the spread of the roots.