Plant Profile: Adiantum (Maidenhair Fern)

Plant Profile: Adiantum (Maidenhair Fern)

By Published November 2022

We have long been fascinated by the simple beauty of maidenhair ferns as well as their amazing worldwide distribution. Often, the same species which are native in the US, are also native on other continents around the world. Many species of Adiantum are found on moist, neutral to alkaline soils, and these conditions make for good garden success as well. Despite their dainty appearance, they are tough, easy-to-grow garden subjects.

The common name “maidenhair” comes from the first of the genus to be described by Linnaeus, Adiantum capillus-veneris, which translates as hair (capillus) + allusion to Venus (veneris) that is typically applied to sexual themes—in other words pubic hair, or the hair that develops when one becomes a maiden. We must remember that Linnaeus was a student of the world, both plant and animal and often referred to plant parts in reference to other anatomical features found in the mammalian world—after all, we also are indebted to him for the genus Clitoria. Perhaps this less PC fact explains the alternative explanation we frequently hear that the term “maidenhair” comes from resemblance of the stems to those on a young maidens head. The name Adiantum comes from the Greek and means ‘not wetting’ referring to the fronds’ ability to shed water. Adiantum often have a rachis and stipe that is a nice contrasting color to the fronds, including chestnut and black. These ferns often have fiddleheads and juvenile foliage that are an attractive pink color.

The genus Adiantum is large, containing around 250 species that both tropical and temperate with centers of diversity in eastern Asia as well as the highlands of South America. The temperate species are easy to grow in dappled shade or even in a site that receives a few hours of sun, as long as the soil stays moist. Adiantum ferns prefer a well drained soil, but in the wild are often found growing on rocks near waterfalls and other areas with seeping water. The U.S. is home to just a handful of species, but these are particularly popular in the horticulture trade (e.g., Adiantum pedatum, Adiantum capillus-veneris).

Adiantum aethiopicum ‘Barrington Belle’ (Barrington Belle Common Maidenhair Fern). This is a hardy form of the typically tropical house plant maidenhair fern. Our plants come from a 2017 David Denton spore collection near Barrington, New South Wales, Australia. In the garden, our 4 year-old plants have formed a 10" tall x 2' wide patch of very dainty-looking, fine green foliage that has remained evergreen through mid-teens F. Though we haven’t had the hardest of winters we’re hopeful that this proves fully capable of taking our zone 7 winters. (Hardiness Zone 7b-10, guessing).

Adiantum aleuticum (Aleutian Maidenhair Fern) Very similar to and hopelessly confused in the horticultural trade with Northern Maidenhair Adiantum pedatum, Aleutian Maidenhair grows in a much cooler climate, ranging in the US from Maine to the Pacific Northwest. In form, it grows and looks very similar to Adiantum pedatum, but in the wild is found on serpentine soils, while Adiantum pedatum can be found on a variety of moist soils, typically rich but mildly acidic in reaction. Aleutian Maidenhair is best separated from its look-a-like by the very short stalks that attach the leaf segments to the stem (0.6 mm or less long) versus the longer stalks (>0.6 mm long) in Northern Maidenhair. As you might guess from the range, Aleutian Maidenhair performs best in cool to cold climates (Hardiness Zone 3-8) and most forms struggle in the heat of the Southeast.

Adiantum capillus-veneris (Southern Maidenhair Fern) This wonderful, vigorous, but slowly spreading deciduous native has hundreds of small triangular leaves on wiry black stems, giving a delicate airy appearance.  The clone that is commonly sold in the trade is actually not a very good form.  While most Americans know this as a southeastern U.S. species, disjunct (isolated) populations can be found in Michigan, South Dakota, Colorado, Arizona, and Texas and in many locations across the globe. It has also found its way into mortar joints between bricks in the old walls of many of our oldest towns such as Charleston and Savannah.We have collected this species in many localities around the world. Interestingly this species was used medicinally when mixed with orange-flower water and honey to make the Syrup of Capillaire as a cough medicine popular in earlier times.  (Hardiness Zone 7b-10, but colder with some of the population disjuncts).

Adiantum capillus-veneris ‘Bermuda Run’ (Bermuda Run Maidenhair Fern) Adiantum capillus-veneris 'Bermuda Run' represents our 2000 wild collection of this wide-ranging species from Bermuda, where we found it growing on a rock wall near the Royal Dockyards. Although we were skeptical about winter hardiness, it has easily survived 6 degrees F so far. Bermuda Run Maidenhair is composed of light green pinnae (fern leaves) held along a 1' long black arching stipe and forms a spreading mat to 10" tall x 4' wide in 10 years. For us, this selection is more compact than most other clones that we have grown. (Hardiness Zone 7b-10)

Adiantum capillus-veneris 'Rock Springs' (Rock Springs Maidenhair Fern) (coll. #A2T-034) This form of the wonderful southern maidenhair fern, Adiantum capillus-veneris, comes from spores that we collected in 2000 in the Edwards Plateau region of TX near the town of Rock Springs. Plantsman Scott Ogden showed us this population growing along a small creek in a very alkaline soil. Our 5-year-old clump is 1' tall by 2' wide and quite heat tolerant. (Hardiness Zone 7-10)

Adiantum caudatum (Walking Maidenhair Fern) This little known Southeast Asian native emerges late after a hard winter, but our plants have survived 7ºF, to form a 5' wide patch in 5 years. The 1.5" wide by 2' long arching fronds, which emerge pink in spring, root into the ground at the tips forming a new plant. Moist soils result in faster growth, but our plants are quite happy in a fairly dry, sandy soil. (Hardiness Zone 7b-10)

Adiantum hispidulum 'Mt. Haleakala' (Mt. Haleakala Rosy Maidenhair Fern) (coll. #A1HA-016) Rosy maidenhair is commonly grown as a houseplant but few gardeners realize its winter hardiness. Although the common Asian form of Adiantum hispidulum is easy to grow and reliable in Zone 8, we were never able to overwinter it outdoors.   Adiantum hispidulum makes an attractive 1' tall by 1' wide clump with fronds which emerge rosy red...hence, the common name. Our spores for this particularly winter hardy collection came from 5000' near the top of Maui's famed Mt. Haleakala. (Hardiness Zone 7b-10)

Adiantum lorentzii 'Salta Splendor' (Salta Splendor Maidenhari Fern) (aka: A.l. A1AG-117) This maidenhair fern hails from the Salta Province of Argentina, at 4100' elevation on the scenic highway west toward the town of Cachi. This variable species is right at home in a lightly shaded woodland garden but has a particular preference for growing on a moist slope. This particularly robust deciduous clump-former makes a 2' tall by 3' wide mound of 3' long glossy arching black stipes that compose the elegant fronds. (Hardiness Zone 7b-10){{image="6136" title="Image of Adiantum lorentzii 'Salta Splendor'" alt="Image of Adiantum lorentzii 'Salta Splendor'"}}

Adiantum monochlamys (Single Cloak Maidenhair Fern) This species, native to dry, rocky cliffs in China, Japan, and Korea is closely related to Adiantum venustum. It reportedly can reach 1’ tall, although 2” in height is all we have been able to achieve. Although not the easiest fern to grow, we have had surprisingly good luck with this.  (Hardiness Zone, guessing){{/image}}

Adiantum pedatum (Northern Maidenhair Fern) Without a doubt, this is one of our most elegant natives. The horizontal horseshoe-like wreath of foliage rests atop 18-24" tall, wiry black stems. Northern maidenhair fern thrives in moist, rich soil but also grows well in all but the driest of garden sites. The light airy texture serves as a perfect backdrop for hostas and other bold foliage plants. In 10 years, expect a 2' wide clump to develop. (Hardiness Zone 3-8)

Adiantum pedatum 'Miss Sharples' (Miss Sharples Northern Maidenhair Fern) A rarely offered English selection of our native maidenhair fern. Miss Sharples has yellow chartreuse foliage (the golden color doesn’t show up in our warm climate) that is slightly wider than the species. The five fingered foliage is held atop the wiry black stems...makes a nice clump with age...best in slightly moist sites. (Hardiness Zone 3-8)

Adiantum raddianum ‘Barberton’ (Barberton Hardy Delta Maidenhair Fern). We never dreamed we'd find a winter hardy form of the typically tropical fern, Adiantum raddianum, but in 2006, we acquired spores from plant explorers Rod and Rachel Saunders, who had collected them at 4,500' in the mountains near Barberton in the Mpumalanga province of South Africa. The tiny, finely-textured pinnae give a tropical feel to this woodland gem, forming a tight 1' tall x 1' wide deciduous clump (evergreen in milder climates). (Hardiness Zone 7b-10, at least)

Adiantum thalictroides 'Argentine Lace' (coll. #A1AG-276) (Argentine Lace Meadow-rue Maidenhair Fern) (syn: Adiantum poiretii) This wonderful selection of the deciduous Meadow-rue Maidenhair hails from Tucuman Province, Argentina around 3500' elevation. The 2' tall, black arching stipes hold the pinnae, which are exceptionally small and dainty on this form. This has proven to be an exceptional clumping maidenhair. (Hardiness Zone 7b-9 at least)

Adiantum venustum (Himalayan Maidenhair Fern) According to Dr. John Mickel, in "Ferns for American Gardens", "The Himalayan maidenhair has become one of the great all-time ferns." This dainty-looking semi-evergreen gem is amazingly cold hardy, but less so in long hot summers, although it has performed admirably in our NC garden when given enough summer moisture. While slow to get started, Adiantum venustum makes a nice 6” tall patch to 3' wide in 5-10 years. Easy to grow. (Hardiness Zone 4b-8a)

Adiantum x mairisii (Mairis’s Hardy Maidenhair Fern) Our first experience with the sterile Adiantum x mairisii was in 1993, thanks to a gift from the late fern collector Nancy Swell of Virginia. Not to be confused with the Chinese Adiantum mariesii, this reported hybrid of Adiantum capillus-veneris and an unknown baby daddy was discovered around 1885 at the UK's Mairis & Co. Nursery and subsequently named by Chelsea Physic Garden Curator and fern collector Thomas Moore. Adiantum x mairisii performs like a vigorous clone of southern maidenhair fern but with very good winter hardiness. Ours formed a 3' wide deer-resistant patch of 1' tall, lacy maidenhair foliage in 5 years. (Hardiness Zone 6a-9b)

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