I'll begin by noting this profile is almost a flight of fancy: the Drynaria ferns, commonly known as oak leaf ferns, are tricky epiphytes that are likely beyond the reach of all but the most dedicated fern enthusiast. That said, they are striking and beautiful plants that are common throughout tropical Asia and the South Pacific, and they find their uses in traditional Chinese medicine. Like many of their epiphytic cousins, they are also exceptionally beautiful plants.
The Drynaria are known for having two types of fronds: a short, sterile, unlobed type that grows around the base of the plant similar to a stag's horn fern, and longer, fertile frond that is deeply pinnate and can be seen hanging from trees and baskets in the tropical world. In terms of growth culture, successful cultivation first requires meeting their unique requirements. Unlike some of the other epiphytes, these are not as totally moisture sensitive—like a staghorn, some moisture is retained in the base of the plant. Nevertheless, handling their watering needs is the hardest part of keeping them thriving.
- Light: These do best in dappled sunlight or even shade. The more light they get, the more reddish coloration is visible in the fronds. In nature, they tend to grow attached to tree trunks.
- Water: They absolutely require a steady supply of moisture and high humidity. Because they are epiphytes, you'll likely have to water every day. They cannot successfully be grown in a container for long.
- Soil: They grow best mounted on tree fern or in a slat container, similar to an orchid. If you're growing in a container, use an orchid mix.
- Fertilizer: Feed with a weak liquid fertilizer throughout the growing season.
Propagation can be accomplished through spores, but this is best left to the experts.
Instead, you can divide larger plants or take pieces of an established plant. Make sure to get both types of fronds and some roots and tie the new piece to a new mount. It should readily begin to grow.
Same as above—as epiphytes they don't really need to be repotted. The plants are best, and most prized, when they have grown to a commanding size. However, in indoor situations or greenhouses, it might make sense to reduce the size of large plants by division.
There are only about 20 species of Drynaria worldwide, all of them concentrated in tropical Asia and the eastern hemisphere. They are commonly used as accent plants in tropical gardens, where their 3-foot fronts emerge from the baskets of sterile fronds and grace trees and baskets alike. The most common species in cultivation is D. quercifolia, commonly known as the oak leaf fern because its fronds somewhat resemble enormous oak leaves.
The growth requirements for these will sound familiar to anyone who has experience with a certain type of demanding epiphyte: plenty of warmth and humidity, no direct sunlight but bright conditions, ample water, and an easy hand with the fertilizer during the growing season.
They are susceptible to cold, but even more susceptible to drought, which will quickly turn them brown and kill them. In general, if you can grow and bloom a vanda orchid successfully, you can probably handle one of these. Same goes for any of the Huperzia species. This generally means that a greenhouse or conservatory is best, although if you are fortunate enough to have a bathroom with a skylight you can make good use of it to produce a small forest of lush epiphytes. Drynaria is vulnerable to pests including aphids, mealy bugs, scale, and white fly. If possible, identify the infestation as early as possible and treat with the least toxic option.