The South American Delta maidenhair fern (Adiantum raddianum, 18-24 inches, Zones 10-11) is arguably one of the loveliest, most delicate house plants you can grow. Its onyx wire-thin stems hold dainty, drooping fronds that tremble at a touch. A few varieties are available–all equally delicate and lovely. One caveat: The plants themselves are on the fragile side, so one has to learn a few tricks to successfully grow them as potted specimens.
About Maidenhair Ferns
A lover of partial shade and humidity, Delta maidenhair fern originates from the tropical Americas, particularly South America and the West Indies, where it naturally inhabits humid forests, rock crevices, rocky streamsides, riverbanks, and embankments as well as shaded cliff faces. It thrives in spots where the soil is moist, fertile, fast-draining, and temperatures are humid and warm. It naturally spreads by rhizomes that creep along rocks. Because of its tendency to naturally spread, it can become invasive when planted in the ground outside of its native territory, so beware planting it in the subtropical southeastern United States (particularly Florida). In such areas, It is best grown as a houseplant or potted specimen.
There are only a few Delta maidenhair varieties available. The lightly variegated Adiantum raddianum ‘Snowflake’ has ivory stripes across the fronds while the extraordinarily hardy ‘Barberton‘ will survive to USDA Hardiness Zone 7.
Sun, Soil, and Water Do’s and Don’ts
When it comes to sun, soil, and moisture for maidenhairs, there are several dos and don’ts.
- Do pick a spot that gets bright filtered light.
- Do place pots in a sheltered outdoor location in summer.
- Do place them indoors in an east, west, or north-facing window.
- Do choose a fertile, well-drained potting mix that’s high in organic matter, like Fafard Professional Potting Mix.
- Do make sure the soil pH is between 6 and 7.
- Do plant ferns in pots with bottom drainage.
- Do keep the soil evenly moist but not waterlogged.
- Do water with filtered or bottled water with low mineral content.
- Don’t let the soil get too dry.
Temperature and Humidity Do’s and Don’ts
Here are temperature and humidity dos and don’ts for maidenhairs.
- Do maintain moderate to high humidity at a level of 50% or higher.
- Do invest in a humidifier if your home tends to be dry or place maidenhairs in a brightly-lit bathroom next to a shower stall.
- Do regularly mist the ferns with filtered or bottled water with low mineral content.
- Do keep the room reasonably warm. Ideal temperatures are between 65-75ºF (18-24ºC).
- Don’t place maidenhair ferns in a location where they are subjected to forced air from drying vents or fans.
- Don’t allow maidenhairs to get cold. If they die back due to the cold, they will sometimes return from the roots, so don’t throw them away immediately.
Other General Care Dos
- Do transplant ferns that have outgrown their pots. (Click here for transplanting and repotting details.)
- Do feed maidenhairs…
- Do trim off stems with browning foliage.
- Do watch out for scale insects, which can attack these ferns.
Follow these dos and don’ts and you will have lush, happy maidenhair ferns to beautify your home.