Feathery and delicate-looking, maidenhair ferns are graceful additions to both indoor and outdoor gardens. They're especially effective when used near water or as a foil to large-leafed shade plants like hostas. Various species of these native ferns can be found throughout most of North America. They're best grown in environments that can be kept shady and damp.
Maidenhairs are deciduous ferns that spread by creeping rhizomes, forming large colonies when well-sited. Each frond has multiple stems arranged in a curving fan shape; the stems are often very dark, highlighting the light green leaflets. Most maidenhair ferns grow in moist woodlands or near streams, and you'll have the best luck growing them when you duplicate those moist, humid conditions.
Growing Hardy Maidenhair Ferns
The northern maidenhair fern (A. pedatum) is the most commonly available type of hardy maidenhair, although on the West Coast you may find the Aleutian maidenhair (A. aleuticum), which is similar in hardiness and growth habit. These ferns grow 18 to 36 inches tall and wide. The light-green, shell-shaped leaflets are held on black or reddish-brown stems. Plant hardy maidenhairs in moist, rich soil in partial to full shade; the Aleutian maidenhair can tolerate full sun if kept well-watered.
The USDA lists these ferns as endangered or vulnerable, so ensure that your garden centre is offering commercially propagated plants, not ones collected from the wild. Both types are hardy in U.S. Department of Agriculture zones 3 through 8.
Growing Tropical Maidenhair Ferns
Other varieties, such as the common maidenhair (A. capillus-veneris) and California maidenhair (A. jordanii), are suitable as outdoor plants only in zones 9 and warmer. These airy ferns grow 2 to 3 feet high and wide and are best planted in large masses. They are neither sun- nor drought-tolerant, so site them in moist, well-drained soil in shade for best results. They're rarely bothered by pests or disease, although they're susceptible to root rot if kept constantly wet.
Growing Maidenhair Ferns Indoors
Maidenhair ferns are difficult houseplants. These fast-growing plants require high humidity and constantly moist, but not wet, soil. Gardeners living in areas that need supplemental winter heat will find keeping the humidity high enough a challenge. Grow the ferns on pebble trays or use a humidifier near them for best results. Ferns that dry out will shrivel, and the leaves will not revive when rewatered, but plants will send up new shoots if the roots aren't badly damaged. Maidenhair ferns grow best indoors in bright light but not direct sunlight, which will scorch the foliage. Keep them between 10 degrees Celsius at night and 18.3 to 21.1 degrees C during the day.