Maidenhair fern, Adiantum raddianum (or sometimes other species in the Adiantum genus) is a pretty, delicate fern that is commonly grown indoors throughout the temperate world.
Though it is commonly grown, however, this fern can be rather tricky to grow, so when trying to grow maidenhair fern indoors, you must understand its needs.
What is Maidenhair Fern?
To understand maidenhair fern, the first thing that is useful to know is where it comes from. Understanding the native environment of these plants can help you to determine the placement and care that they require.
Maidenhair ferns can be any ferns within the Adiantum genus, which are found in the Americas, eastern Asia, and New Zealand. Though there are around 250 species within the genus, only a handful are commonly grown by gardeners, or as houseplants indoors.
Among these, the most commonly grown in temperate climates indoors are the tropical species A. raddianum and A. peruvianum. A. raddianum is the most common – one of the most popular ferns to grow indoors.
Hardier ferns in this genus can also be grown as houseplants as well as being cultivated outdoors. Though North American natives like A. aleuticum and A. pedatum are best grown outside in a garden, they are also sometimes grown indoors.
These ferns have pinnately divided fronds with fan-shaped, oblong, or rounded segments. They can be deciduous or evergreen and evergreens are often most popular for indoor cultivation.
Where to Grow Maidenhair Fern
Choosing the right place to position a maidenhair fern that you are growing indoors is the first and in many ways most important part of the puzzle. These are delicate and somewhat fussy and so do need the right conditions to thrive.
One important thing to understand is how much light maidenhair ferns require. These plants, like many other indoor ferns, need bright but indirect light in summer. But in winter, evergreen types will require full light to thrive and should be positioned in as light a location as possible.
Temperature & Humidity Requirements
Maidenhair ferns like A. raddianum require a warm and humid location. Temperatures should ideally remain at all times between 15 and 21 degrees Celsius. They must never fall below 10 degrees when growing a tropical maidenhair fern species.
The temperatures should not fluctuate too much, so don’t put these plants in a draught, or too close to a radiator, stove, or other heat source.
Humidity must be high for these ferns, and so they are an ideal choice for a terrarium, or for placement in a bright and frequently used bathroom. Where humidity is not high enough, it is a good idea to group houseplants together, to mist regularly, and to stand the pot on a saucer of water and pebbles.
Soil/ Growing Medium
Maidenhair ferns need moisture-retentive yet well-drained soil. You can plant one of these ferns in any reasonably moist peat-free potting mix. Ideally, this mix should be neutral or slightly alkaline in pH.
Planting Maidenhair Fern
You might obtain a maidenhair fern through propagation by division of an existing plant. Rhizome division is undertaken in the early spring. Spores can also be sown as soon as they are ripe, and kept at a minimum of 21 degrees Celsius so that new plants can form.
Of course, you might also purchase a fern of this kind in a pot. When repotting a plant purchased in a pot, make sure that the root ball is just above the surface of the surrounding medium. Water the new plant in well but make sure that excess water can drain away freely.
Caring for Maidenhair Fern
These ferns do have a reputation for being more challenging to care for than many other ferns that you might grow indoors. But with the right care, these can be rewarding houseplants to grow.
Your goal when watering maidenhair ferns is to make sure that the growing medium remains moist but not waterlogged at all times. Keeping this fern in the Goldilocks zone does require some vigilance and careful watering so as not to water too much or too little.
Make sure drainage remains adequate and that whenever you water excess water can drain away freely.
Ferns don’t typically require much feeding. But if growth seems poor or you believe there is a nutrient deficiency then you can feed during spring and summer, around once a month. Choose a dilute, organic, balanced liquid plant feed to do so.
It is common for problems experienced when growing maidenhair fern to be related to issues with water, or other environmental factors.
For example, brown leaves other than the ones forming naturally at the bottom of the plant might be due to low humidity, draughts, or temperature fluctuations due to a heat source nearby, drought or low water availability, or harsh sun. Leaves can also turn brown if they are touched too much.
Pale leaves typically mean too much or too little sunlight. But these can also indicate that the plant requires feeding.
Yellow leaves can also be a sign of extreme temperature fluctuations, or due to either under or over-watering.
In addition to these environmental issues, those growing maidenhair fern may also see pest problems. Scale insects, for example, can look like raised brown spots on the leaves. Mealybugs can be spotted below leaves looking like white, fluffy lumps.
Repot maidenhair ferns every year or two, whenever the roots of the plant have filled the pot. It is best to repot these ferns in the spring and to choose a new container that is just slightly larger than the old one.