How to Plant, Grow, and Care for Tree Ferns

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.

Overview

Plant type Houseplant, evergreen in temperate and tropical zones Sun Exposure Dappled or filtered light – no direct sunlight	Watering requirements Weekly watering and high humidity Maintenance Low	Soil Type neutral to slightly acidic (pH 5-6), humus-rich and well-drained soil  Fertilizer monthly applications of organic fertilizer during the growing season

History

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.

Varieties

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. 

Tasmanian Tree Fern

	common name Soft tree fern
	botanical name Dicksonia antarctica
	genus Dicksonia
	height 12-18 feet
	hardiness zones 9-10

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.

Australian Tree Fern

	common name Lacy tree fern, Australian tree fern
	botanical name Sphaeropteris cooperi
	genus Sphaeropteri
	height 15-30 feet
	hardiness zones 8-11

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. 

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. 

Other Species

Rough Tree Fern

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. 

Hawaiian Tree Fern

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.

Characteristics

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.

Underneath the blades of the fronds, you’ll see tiny raised red bumps called sori, which contain spores, the plant’s reproductive structures.   

How to Grow

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.

Planting

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.

Light

Remember that since they’re understory plants in their native habitats, they’ll do best with dappled or filtered light. Too much direct sunlight can cause the leaves to crisp and burn. 

Temperature

If planted outside, D. antarctica can withstand temperatures down to 17°F (-8°C), while S. cooperi can only withstand temperatures down to 28°F (-2°C). Generally, warm areas like central and southern Florida, southern Texas and Louisiana, and parts of southern California are suitable habitats for outdoor planting. D. antarctica is sensitive to temperatures above 95°F (35°C), so S. cooperi would be a better option for hotter areas.

If you live in a borderline climate where temperatures rarely dip below the minimum suitable temperatures, these warm-weather-loving plants can be overwintered by wrapping the trunk and fronds with horticultural fleece and twine and filling the crown with straw. Standard horticultural fleece provides protection to 0°F (-18°C), so if your winters get colder than this, keep your fern potted and move it inside for the winter. 

They thrive in warm, humid environments, so a shady area with high humidity would be the perfect place for your fern in the summer.

Soil and Fertilizer

Use a well-draining soil that’s neutral or slightly acidic and rich in humus, dark organic matter made up of decomposed plant and animal matter. Try to mimic the soil of the rainforest – compost, seaweed fertilizer, fish emulsion, manure, or earthworm castings all make great organic fertilizers for these native Australian plants.

During the growing season (late spring through summer), a monthly dose of diluted fertilizer will help produce healthy fronds. If they start turning from a rich, vibrant green to a diluted, yellowy shade, your fern needs to be fed.

Humidity

Ample humidity is the number one key to a thriving tree fern – the trunk is composed of tiny, hair-like aerial roots that absorb moisture. Droopy, crispy, and/or falling fronds are all signs your fern doesn’t have adequate humidity – here are some tips to make sure your D. antarctica or Sphaeropteris cooperi stays humid and happy: 

Basically – you’ll want to create a mini sauna minus the extreme heat.

Water

Felicia met her demise when I forgot to leave my well-meaning plant sitter instructions on her misting protocol – she was beyond saving when I returned. To my horror, her leaves were crispy, and the soil was sopping wet. In addition to leaving instructions on their unique care, here’s how to prevent the same tragedy:  

The spray (even better – mist) attachment on your watering apparatus will be your best friend. Once a week, give the trunk a deep watering to let those trunk hairs absorb moisture and let the excess water filter into the soil. Keep the soil moist, but not soaking wet. Avoid watering the crown (where fronds unfurl), as this can lead to fatal crown rot. 

To prevent overwatering and root rot, always double-check for moisture before watering by dipping your finger two inches into the soil (the top layer should be dry) or by using a soil moisture meter.

Maintenance

These plants don’t need any pruning – as the plant ages and grows taller, the older fronds will die off and can be clipped at the base for aesthetics and used as mulch or compost. If you’re keeping your fern outside – keep the fronds intact to protect the trunk from harsh elements and cooler temperatures.