Maidenhair ferns (Adiantum raddianum) are deciduous ferns known for their delicate, fan-shaped leaf segments clustered on wiry black stems. They’re a popular houseplant known for their attractive foliage and compact size. Maidenhair ferns can grow anywhere from one to two feet tall and wide at maturity, with a lifespan of around 15 years.
I. Appearance and Characteristics
Adiantum raddianum, the Delta maidenhair fern, is one of the most popular ferns to grow indoors. It is native to South America and its common name comes from its shiny, dark leafstalks that resemble human hair. It typically grows about 17–19 in (43–48 cm) tall and up to 22 in (56 cm) wide. In the wild, it is found on forest floors, rock crevices, river banks, coastal cliffs, and basalt banks along trails and streams. The triangular fronds are semi-erect in the beginning then droop gracefully as they age and can be up to 12 inches (30 cm) long by 6 inches (15 cm) wide. The genus name Adiantum comes from the Greek word “adiantos”, meaning “unwetted” (in reference to the leaves).
This plant is hardy down to 5 °C (41 °F), so must be grown indoors in temperate regions. However it may be placed outside in a sheltered spot during the summer months. It requires high humidity, well-drained soil, bright indirect light, and a fairly constant temperature. It prefers neutral or slightly alkaline soil and is suitable for USDA hardiness zones 10 and 11. It can be susceptible to scale and mealybug. The cultivars ‘Brilliantelse’ and ‘Kensington Gem’ have won the Royal Horticultural Society’s Award of Garden Merit.
A. raddianum is sometimes considered invasive in Hawaii and French Polynesia.
II. Types of Maidenhair Fern
Maidenhair fern is part of the Adiantum genus that includes over 200 types of ferns grown around the world. The genus name is derived from the Greek word adiantos, which means “unwetted”—an apt description for the fern since its leaves repel water. Here are a few common varieties of maidenhair fern.
- Northern Maidenhair Fern (Adiantum pedatum): This species, found in eastern North America and in parts of Asia, is a popular outdoor plant for shade gardens.
- Western Maidenhair Fern (Adiantum aleuticum): Also called Aleutian maidenhair fern, this species is native to the west coast of North America. It often grows near waterfalls where the plant can benefit from the spray.
- Southern Maidenhair Fern (Adiantum capillus-veneris): This species is sometimes known as Venus maidenhair fern. It’s commonly found in the southern United States and elsewhere in the world in temperate and tropical regions.
III. How to Grow and Care
Sunlight
Mimic the conditions of this lower-light plant’s natural forest floor environment by putting it in a place that receives indirect sunlight. Avoid harsh light or direct sun, as its delicate leaves can burn very easily. However, too little light leads to poor growth and yellowing fronds.
Temperature and Humidity
Give maidenhair ferns plenty of warmth and humidity to mimic their native conditions. To increase humidity, place the potted plant near a humidifier or in a bathroom that gets regular steam from the shower.
Temperature-wise, keep this fern above 70°F. Avoid placing it near cold drafts or anywhere in your home where the temperature could dip below 60°F.
Watering
Keep your maidenhair fern’s soil consistently moist but not soggy. Water regularly to keep the soil from drying out, but never let the plant sit in water that collects in a drip tray or cache pot. Moisture is vital, but drainage is important to avoid root rot. Watch for yellow leaves that may occur from overwatering.
Soil
Give your maidenhair fern moist but well-draining potting soil. Increase your chances of creating the proper environment for this plant by incorporating organic matter, like compost, into the soil to help it retain water.
Fertilizing
Skip fertilizing your maidenhair fern—the plant will do just fine without it. However, if you wish to provide an added dose of nutrients, you can feed with a balanced, diluted blend of fertilizer once a month. Avoid fertilizers that are high in nitrogen, which can cause the tips of the leaves to burn.
Pruning
There’s no need to prune maidenhair fern regularly, but it’s a good idea to remove dead or damaged fronds as they appear. Cut them off at the crown of the plant to give the healthy growth more light and keep your plant looking tidy.
Propagation
Like other ferns, maidenhair ferns are easy to propagate by division. You’ll need a few plant pots, fresh potting mix, and a clean, sharp knife. Here’s how to propagate maidenhair fern.
- A few days before you want to divide your fern, water it well.
- When it’s time to propagate, fill the new pots about a third of the way with fresh soil. Remove your maidenhair fern from its container.
- Use a clean, sharp knife to cut the root ball into two or three clumps, ensuring that each clump has a portion of the rhizome and foliage. You can take this opportunity to cut back any dead or damaged fronds from the crown of the plant.
- Plant each section into its own pot. Fill in each container with fresh soil.
- Water the divisions well. Wait a couple of months to fertilize recently divided ferns, as this can burn the roots.
Potting and Repotting
Maidenhair ferns can be repotted annually or biannually, depending on the pot size and the plant’s growth rate. They’re slow growers and don’t mind being a little crowded, so don’t rush to repot them if you’re unsure.
Instead, wait for signs that your fern is outgrowing its home, like the roots filling up the pot. Use a plastic or glazed ceramic pot with drainage holes, and only go up one or two inches in diameter when repotting into a larger container. Avoid terra cotta pots, which wick away moisture and dry out the soil too quickly.
Pests and Diseases
Common Pests
Only a couple of common insects usually affect indoor maidenhair ferns. Scale and mealybugs like to attach themselves to the fronds. Check the plant regularly and treat any infestation with insecticidal soap.
Common Problems
Maidenhair ferns can be affected by underwatering, too much sun, and lack of humidity. Revive a maidenhair fern by placing it in an area with bright, indirect light and watering consistently so that the soil is moist but not soggy. Make sure the pot has sufficient drainage to prevent root rot. Remove any dead or damaged fronds to tidy up the plant’s appearance and support new growth.
Leaves Turning Brown
This is a common sign of overly dry conditions—lack of water, lack of humidity, or both. Check the soil moisture and water the plant if needed. Consider running a humidifier in the space to add moisture to the air, and make sure the plant isn’t located in the path of a heat or air conditioning vent.
Leaves Turning Yellow
Yellowing leaves on maidenhair ferns often signal overwatering. Allow the soil to dry out before watering again. In extreme cases, it may be best to repot the plant with fresh soil, removing any dead or rotten roots while repotting.
Leaves Falling Off
If a maidenhair fern is allowed to dry out too much, leaflets will turn brown and crispy and eventually fall off. Trim away damaged foliage, water the plant deeply, and consider running a humidifier. Monitor soil moisture and water again before the soil dries out.
Leaves Curling
Curling leaves are another sign that your maidenhair fern needs higher humidity. You can try grouping it together with several other humidity-loving plants, keeping it in a bathroom where steam from the shower can boost humidity, or running a humidifier nearby.
III. Uses and Benefits
Maidenhair ferns is a great choice for beds and borders, underplanting shrubs and roses, or containers.