Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
My favorite fern is the maidenhair fern which unfortunately is not hardy in my growing zone. In temperate climates, we have to grow it as a houseplant.
What are Maidenhair Ferns?
Maidenhair ferns (Adiantum raddianum), also known as Delta maidenhair ferns, are native to South America. Their natural habitats include forest floors and rock crevices or along shady riverbanks and streams. They are only hardy in zones 10 and 11.
They are small ferns, only growing to 1 to 2 feet tall and 1 to 2 feet wide. They are slow growing and can take up to three years to attain their full size.
The individual fronds can be up to 6 inches wide. They start by growing vertically, but as they mature, gracefully droop towards the soil. What I love about them is that each frond has a stem from which hang what looks like small leaves. They look a lot like columbine leaves. The stems are what give the ferns their nickname “maidenhair.” They are said to look like hair.
Because they are true ferns, they do not flower. They reproduce by spores which can be found on the undersides of the leaves.
How to Grow Maidenhair Ferns Outdoors
If you are fortunate enough to live in growing zones 10 and 11, you can grow maidenhair ferns in the shady corners of your yard. Try to mimic their natural growing environment with a partial shade area. Tuck them into corners and crevices or around the shady side of your garden pond.
Their native environment is shady and wet, so they are a good plant for that spot in your yard that is always damp. The soil should be well-drained. These ferns like to be damp, but not soggy. Maidenhair ferns prefer acidic soil. Have a soil test done to see what the pH of your soil is and add any amendments needed to make it slightly acidic.
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These ferns need high humidity so if you live in a dry area of the country, you will need to mist your plants regularly.
How to Grow Maidenhair Ferns Indoors
While they may be hardy outdoors in a southern garden, maidenhair ferns are a little trickier to grow indoors. Grow your fern in a room with indirect light. Direct light or the harsh rays of a southern window will burn the leaves of your plant.
You can use regular potting soil but you might want to add a bit of moss or organic compost to help the soil retain moisture. You don’t want water just to pass through the soil. To help keep your soil moist, you should water your fern every day or every other day. Don’t allow it to dry out. If the soil dries out, the foliage will dry out and won’t rehydrate when you start watering again. If the leaves are hydrated but start to turn yellow, you are over-watering and need to cut back.
Probably the most difficult part about growing maidenhair ferns indoors is making sure that they get enough humidity. Our homes are much too dry for them. You will need to mist your plant multiple times a day. You can also provide humidity with a humidity tray which is a shallow pan filled with ornamental gravel and water. Place your fern on top of the gravel (not in it). As the water evaporates, it provides humidity to your plant. Be sure to keep the tray filled with water at all times.
Maidenhair ferns are sensitive to chemicals. Try watering with either distilled water or rainwater that you have collected from outdoors. Distilled water is purified water. It has been heated until it turns to steam, leaving the chemical impurities behind. The steam is then condensed back to water form without the impurities.
Maidenhair ferns are also sensitive to the soluble salts found in most commercial fertilizers. Use a liquid fertilizer that is formulated for houseplants diluted to ¼ strength. Fertilize every 4 to 6 weeks during the spring and summer growing season. Do not fertilize during the fall and winter when the plants are not growing.
You can move your maidenhair fern outdoors during the summer once the nighttime temperatures are above 70°F. Bring it back indoors in the fall when the nighttime temperatures start to fall below 70°F. Be sure to put in a shady spot. Too much sunlight will burn the leaves.
How to Divide Maidenhair Ferns
Maidenhair ferns grow very slowly so you don’t have to worry about repotting them too often. In fact, they don’t mind being a little pot bound so you can wait until the roots have completely filled the pot. When that happens, it’s time to repot into a larger pot.
It’s also a good time to divide your fern. To divide your fern, carefully remove it from its pot. Use a sharp knife to cut the root mass into smaller pieces. Make sure that each division has both roots and fronds attached to it. Plant each division in its own pot.
© 2022 Caren White