Adiantum

( ad - ee - AN - tum )

At-A-Glance Information

Commonly called Maidenhair Fern, these plants need partial to full shade and ample amounts of water to perform well in the garden. Most species in this genus hail from moist tropical areas and form spreading clumps of greenery that over time form large colonies. Stems are wiry and dark, and leaves are fan-shaped, bright green, and intricately divided. These ferns have a lifespan of about 15 years, and are great when used as accents among low-growing shade plants or as edgings near pools of water. Indoors, these ferns are air-purifiers, and are safe to keep around pets and children.

Adiantum Species and Varietals

The genus Adiantum is a member of the plant family Pteridaceae and includes around 250 distinct species. The name of the genus is derived from the Greek word meaning 'unwetted', referring to the fronds' ability to shed water without becoming wet. The best growing zones for Adiantum vary by species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Adiantum aethiopicum (Common Maidenhair Fern, Bush Maidenhair Fern)
These small ferns have a widespread native range, including Africa, Australia, Norfolk Island and New Zealand. They have the potential to form large colonies, and are typically found near creeks or in open forested areas. These are popular garden ornamental plants, and reach up to 18 inches tall when mature. This species does well in USDA growing zones 9a-11b.

Adiantum aleuticum (Western Five-Finger Fern, Western Maidenhair, Aleutian Maidenhair)
This species grows best in USDA hardiness zones 3-8 or Sunset zones 1-7 and 14-21, and is native to western North America. Fronds have a finger-like pattern and sit on slender stems that reach 1 to 2.5 feet in length. This species is a great choice for shaded planting beds, but can also take some sun if well-watered.

Adiantum atroviride (Maidenhair Fern)
These plants are endemic to Australia, and are small with short, creeping rhizomes. Fronds reach 30 inches long and are intricately divided into fan-shaped divisions. It was first described by Australian botanist Peter Dundas Bostock. This species grows well in USDA hardiness zones 9b-11b.

Adiantum bellum (Bermuda Maidenhair Fern)
This species is native to Bermuda, where it is the most prolific fern on the island. These deciduous ferns grow in crevices, on cliffs, and under rock edges, and produce fronds that reach about a foot long. These plants are sometimes grown in gardens, though it does much better indoors or in a greenhouse in most places.

Adiantum capillus-veneris (Southern Maidenhair, Black Maidenhair Fern, Venus Hair Fern)
Best in USDA hardiness zones 5-8 and Sunset zones 5-9, 14-24, H1 and H2, this fern is native to the tropical and warm temperate regions around the world. Individual plants get to 1.5 tall and just as wide. Leaflets are small and fan-shaped, giving the plant a dainty look, even though the plant is hardy, durable, and easy to grow. These are popular indoor and outdoor ornamental plants.

Adiantum caudatum (Walking Maidenhair, Tailed Maidenhair, Trailing Maidenhair)
Native to partially shady areas in Bangladesh, Burma, India, Nepal, Philippines, Thailand, China, and Vietnam. This species prefers moderate levels of light and is not cold-hardy. Trailing Maidenhair does well in hanging baskets, where its fronds can be on display. This species is best in USDA hardiness zones 7b-10.

Adiantum concinnum (Cilantrillo, Culantrillo, Brittle Maidenhair Fern)
These ferns have a native range that spans from northern Mexico to eastern areas of Brazil, and have been introduced to many other areas of the world, including India, Sri Lanka, Hawai'i, and Tanzania. These are humidity-loving ferns, and do not do well in cool, dry temperatures. These plants are used as a local herbal medicine in many South and Central American cultures. Fronds grow to reach 37 inches long. Best in USDA hardiness zones 9a-11b.

Adiantum formosum (Giant Maidenhair, Black Stem Maidenhair)
This species is native to Australia and New Zealand. They are popularly grown as ornamentals due to their beautiful foliage. They go dormant in cooler months and grow rapidly during summertime. There is a variegated cultivar that is commercially available. Best in USDA growing zones 8-10.

Adiantum hispidulum (Rosy Maidenhair, Rough Maidenhair, Five-Fingered Jack)
This native to the tropics of Asia and Africa is best as an indoor or greenhouse specimen. Gets about 1 foot tall, with rosy-brown young fronds that turn medium green with age. These ferns adapt well to most climates, but can be slow-growing in places that are overly cold. It is more tolerant of sun and drying out than other species. It is hardy down to 23 degrees Fahrenheit. These plants do well in USDA hardiness zones 7b-10.

Adiantum jordanii (California Maidenhair, Jordan's Maidenhair Fern)
These ferns are native to California and Baja California, and produce fronds that reach 20 inches tall. They are great ferns for native plant and wildlife gardens, though their sale is monitored due to the fact that they are carriers of Phytophthora ramorum, which causes Sudden Oak Death. When sold, these plants must be identified by their place of origin and have a phytosanitary certificate. Do not take cuttings from wild specimens, as this may spread the deadly disease.

Adiantum pedatum (American Maidenhair Fern, Five-Fingered Fern, Northern Maidenhair Fern)
This fern grows best in USDA hardiness zones 3-8 and Sunset zones A3, 1-7, 14-17 and is native to eastern North America, where it grows in moist forested areas. They produce shiny black stems and light green fronds, and are very cold hardy and are nice spreaders; great for planting beneath deciduous trees.

Adiantum raddianum (Adiantum cuneatum) (Delta Maidenhair Fern)
This native of Brazil is best grown indoors or as a greenhouse specimen, though it can be moved outdoors during the summertime. Reaches to 15-18 inches tall at maturity. Varieties include 'Fritz Luth', 'Gracillimum' (with very finely cut foliage, pictured right), and 'Pacific Maid'. This species does well in USDA zones 9b-11b.

Adiantum reniforme (Lotus-Leaved Maidenhair Fern)
This species prefers growing in sheltered rock crevices and on walls, and is native to East Africa, Madagascar, Mascarene Islands, Comoros, Chad, and the Madeira, Canary, and Cape Verde Islands. Best in USDA hardiness zones 10 and 11, and otherwise grown as an indoor or greenhouse plant.

Adiantum venustum (Himalayan Maidenhair, Evergreen Maidenhair)
This fern grows best in USDA hardiness zones 4b-9 and Sunset zones 3-7 and 14-17. These plants are native to China and reach 6-8 inches high and spreads slowly to 5 feet wide. Great as a groundcover. New leaves are bright pink-bronze and mature to green. Should be sheared in late winter to spur new growth. Very easy to propagate by division.

Adiantum viridimontanum (Green Mountain Maidenhair Fern)
These ferns are native to New England and eastern Canada, and prefers to grow in serpentine soils unlike many of its other genus-mates, who prefer moist woodlands. They prefer sunny areas with thin soil layers over rock, and are long-lived. Individual plants reach between 1 and 2 feet tall with 12 to 30-inch long fronds. The species is considered vulnerable to extinction, and should only be purchased from reputable growers.

Caring for Adiantum

Springtime is the best time of the year to plant Maidenhair ferns in the landscape, when temperatures have risen above freezing. Maidenhair ferns need to be situated in full to partial shade for best results; ideally, they should at most be getting filtered sunlight outdoors. They prefer to be planted in fertile, well-draining but moist soils in areas with high humidity. If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. The ideal soil pH for these ferns is between 6.0 and 8.0.They can be a little bit finicky outdoors, as their humidity requirements are difficult to replicate in most temperate zones around the world; choose a sheltered space in the garden that is not drafty for best results. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. Mature Maidenhair Ferns also need regular waterings, and should only be allowed to dry out slightly between irrigations.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Prune off any damaged, diseased, or dead growth in springtime to clean up the look of the plant and improve airflow. Divide plants every 3-5 years or when they are overcrowding their allotted space. For instructions on how to successfully divide Maidenhair ferns, see the Propagation section below.

Growing Adiantum in Containers
Adiantum, or Maidenhair Ferns, do well in the ground as well as in containers. Choose a container that has adequate drainage holes on the bottom and is about 2 inches larger than the root ball. Fill the container with well-draining potting mix amended with plenty of organic material, compost, and vermiculite. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly; Maidenhair ferns grown in containers will require more frequent irrigation than those grown in the ground. Fertilize yearly in early springtime with an application of 1 inch of compost around the base of the fern. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. Prune to remove dead, damaged, or diseased foliage at any time during the growing season. Every few years, these ferns will need to be taken out of their pots and divided. For instructions on how to successfully divide Maidenhair ferns, see the Propagation section below.

Growing Adiantum Indoors
Place your Maidenhair Fern in a place indoors that receives bright but indirect sunlight. Avoid direct sun, even through windows, as the delicate leaves on these plants can burn easily. Too little light, on the other hand, can lead to poor, slowed growth and yellowing fronds. Soil should be well-draining and fertile, but able to hold a good amount of moisture. Keep soil consistently moist but not soggy. Provide regular waterings to keep the soil from drying out, and make sure to empty the tray or cache pot underneath the nursery pot afterwards to avoid having standing water around the roots. Keep the temperature around these ferns at above 70 degrees Fahrenheit, and avoid placing them in a spot where they will receive drafts of cold air, either from outdoor air or vents. These plants love humidity, and do well in kitchens and bathrooms where humidity is naturally higher.

Propagation

Adiantum ferns are best propagated via division. This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil, compost and/or other organic material, and pots. Division is best done in spring or fall (after the plant has entered dormancy but before it has begun its new spring growth), and needs to be done every few years regardless of whether you have the goal of propagating the plants for best results. To propagate by division, follow these steps:

Gather your materials. Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the roots. Once you have worked it up out of the ground, lay it out.
Start to tease apart the roots with your fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root section.
Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost or other organic material to complete this task. Then, plant your divided ferns in soil at the same height as they were previously, and water thoroughly.
Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout.