If you’re looking for a plant with beauty as rich as its history, a tree fern just might be your answer. Garden expert Christina Conner has all the details on caring for these gentle giants.
When I was in college, my first big plant purchase (meaning – not rescued from the clearance rack or a mystery propagation) was an Australian tree fern named Felicia. Her lacy, delicate fronds added a Jurassic vibe to my indoor jungle of big-leaved banana trees, pothos, and fiddle-leaf figs.
There are over 650 species worldwide. They’re endemic to the understories of tropical, sub-tropical, and cool temperate climes throughout the world. They tower in the rainforests of Queensland, Tasmania, Hawaii, New Guinea, and New Zealand. Tree ferns thrive where the air is humid, and the soil is rich with organic matter.
Though beautiful, this is a finicky plant that would be a great option for an intermediate or advanced gardener. They require a lot of humidity and careful watering, which may prove challenging for a beginner gardener. Though Felicia didn’t survive the occasional neglect during holiday breaks and hectic finals weeks of my college years, my love of tree ferns remains.
Tree ferns are older than dinosaurs. They predate the Jurassic period and go back at least 200 million years to the Triassic period, evolving alongside plants that became known as fern allies, like Equisetum hyemale, also known as Horsetail Rush. Incredibly, these Australian plants have even evolved to survive bushfires thanks to millennia of evolution and protection via their woolly, moist trunks. The unfurling of bright green fronds after a fire is a beautiful sign of resurgence.
This article will focus on how to plant, grow, and care for the most common varieties found in plant stores: the Tasmanian Dicksonia antarctica and the Australian Sphaeropteris cooperi.
D. antarctica can grow up to 30 feet in the wild, but cultivated varieties top out at about 12-18 feet. This southern Australian plant is more resistant to colder temperatures than other tree ferns, specifically S. cooperi.
The Tasmanian variety is on the shorter side. It’s very slow growing – depending on the environment, one to three inches of growth can be expected per year.
The more tropical of the two, S. cooperi stretches from the temperate rainforests of New South Wales to tropical far north Queensland. In its native areas, they grow up to 50 feet, with fronds stretching over 10 feet long. This is also the faster growing of the two. It can grow anywhere between half a foot to three feet per year, depending on the environment.
While some gardeners have had luck overwintering Sphaeropteris cooperi in zone 8, some have experienced dieback during cold snaps. For this reason, we recommend planting it as a perennial only in zone 9b and above.
Note: This plant also recently underwent a name change from being known as Cyathea cooperi. You might see nurseries and plant sources still refer to this Australian plant by its former name.
Hailing from southern Queensland, this species prefers cooler climates and can be found in drier mountain areas. This Australian plant is slightly hardier than other species and can even tolerate direct sun. Its namesake, Rough Tree Fern, comes from the distinctive remnants of old fronds on its trunk.
This tropical plant is native to most of the Hawaiian islands but is under threat from invasive species, deforestation, and overharvesting for gardening media. If you live in Hawaii, consider incorporating a Häpu‘u into your landscape. Note: S. cooperi should not be planted in Hawaii as it’s invasive and outcompetes native species.
Despite the name, these ferns aren’t truly trees. Its “trunk” is one big modified rhizome covered with tiny hairs that absorb moisture and nutrients. From the crown, crosiers unfurl from a tight spiral over a few weeks to reveal new leaves called fronds. As they age, they drop, and new fronds continue to emerge in a slow cycle that builds height and turns young, shrublike plants into towering giants.
The best way to acquire these Australian plants is to either buy from a nursery or online retailer or start from spore. Spores can be sourced from a friend or reputable source, like the American Fern Society spore exchange – the sooner you start a spore after collection, the better.
To learn more about collecting and germinating spores, check out our article on Sword Ferns – these spore collection tips also work for other species.
Whether you plant your fern indoors or outdoors will depend on climate and personal preference – D. antarctica does well in USDA zones 9-10, and S. cooperi does best in the temperatures in zones 8-11. That said, both species are great as houseplants, so fear not if you live in a different region.