Athyrium niponicum var. pictum, or Japanese Painted Fern, is a colorful deciduous fern that is native to China, Japan, and Korea. The fronds are a soft metallic grey, suffused with reddish or bluish hues. They will reach 8 to 20 inches (20-50 cm) tall and spread by underground rhizomes. The ferns are very cold hardy and will grow outside in USDA zone 4-9.
Culture: Athyrium niponicum var. pictum need partial shade to full shade, with a rich, moist soil mixture. In the greenhouse, we use a soil mix consisting of 2 parts peat moss to 1 part loam to 1 part sand or perlite. During the growing season, the ferns are kept moist for optimum growth. They are fertilized every 2 weeks using a balanced fertilizer. In late September, the ferns are moved to a cool room for their winter dormancy period. The temperature of the cool room stays about 48°F (9°C) and the containers are allowed to dry slightly.
Propagation: Athyrium niponicum var. pictum are easily propagated from spores or by division. The ripe spores can be collected on a piece of paper placed underneath spore-bearing leaves. Sow spores on damp peat moss in late winter. The spores germinate best at a temperature of 68-70°F (20-21°C). The growing medium should be kept constantly moist (the sexual phase, known as a gametophyte or prothallus, is only 1-cell thick over much of its body). To protect these fragile plants, it is best to cover the container with glass or plastic. Once new plants are large enough to handle they can be transplanted into individual containers.
Athyrium niponicum var. pictum was featured as Plant of the Week October 1-7, 2004.
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