Growli
Let's go

Plant care

Australian Tree Fern (Lacy Tree Fern) care

Cyathea cooperi

Also called Australian Tree Fern, Lacy Tree Fern, Cooper's Tree Fern.

RHS H2USDA 9-11Pet-safeIndoor Trunk 3–5 m (10–16 ft) tall outdoors

Watering rhythm

Bright indirect light (just back from a sunny window)

2-3 times per week; increase in heat and wind

Jump to schedule→Get smart reminders in the app

Light

Bright indirect light (just back from a sunny window)

Soil

Humus-rich, freely draining, moisture-retentive

Humidity

60–80%

Temp

10–28°C

Pet safety

Pet-safe

Mature size

Trunk 3–5 m (10–16 ft) tall outdoors

Care at a glance

Light

In the wild australian tree fern grows on the bright edge of a forest canopy, not in the canopy and not in the open. Indoors, that translates to within a metre of an unobstructed window, sheer curtain optional. Grows in rainforest margins and tolerates more sun than most tree ferns. Bright, filtered light is ideal. In cooler climates, some morning direct sun is beneficial. In hot regions, protect from harsh afternoon sun, which scorches the delicate fronds. The fastest test: a hand held at the leaf casts a soft-edged shadow at noon — sharp shadow means too much sun, no shadow means too little light.

Watering

Aim for 2-3 times per week; increase in heat and wind for australian tree fern, but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Keep roots consistently moist. The trunk should be kept damp — water it directly during dry spells. Fronds wilt rapidly when the plant dries out. In windy, hot conditions, water daily. Reduce in cool winter months.

Soil and pot

Australian Tree Fern grows best in humus-rich, freely draining, moisture-retentive. Well-amended garden soil with added compost, bark chips, and perlite. Slightly acidic pH 5.5–6.5. Avoid heavy clay. In containers, use a premium potting mix with added bark and perlite for drainage. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Australian Tree Fern sits happiest at around 60–80% humidity and 10–28°C (50–82°F). Appreciates high humidity but is more adaptable to drier air than many ferns. Regularly mist fronds and trunk in dry conditions. Frond margins brown quickly in low humidity combined with heat or wind. If you keep the room above 10–28°C year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed australian tree fern sparingly. Feed every 4–6 weeks during spring and summer with a balanced liquid fertiliser at half strength. Slow-release granules worked into the soil surface in spring are an effective alternative. Do not fertilise in winter. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on australian tree fern in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Wind scorch on frond margins — Fronds are large and delicate; exposed positions or dry winds cause rapid browning of frond margins. Site in a sheltered spot and keep humidity high. Damaged fronds will not recover — remove and allow new growth to replace them.
  • Scale insects on trunk and fronds — Various scale species colonise trunk and frond undersides. Treat with horticultural oil or neem oil spray; heavy infestations may need a systemic insecticide. Inspect regularly as colonies can establish quickly in warm conditions.
  • Crown rot — Standing water or overwatering at the crown (growing tip) causes rot, often lethal. Water the root zone rather than pooling water in the crown. Ensure excellent drainage. Do not mulch directly against the trunk base.

Propagation

Propagated by spores: collect brown spores from the underside of mature fronds and sow on moist sterilised peat at 20–24°C under high humidity. Germination takes weeks to months; plants reach transplantable size after several months to a year. Division is not a practical propagation method. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Australian Tree Fern is pet-safe. Cyathea cooperi is not listed as toxic by the ASPCA. True ferns in the Cyatheaceae family have no documented toxic principle to dogs or cats. Ingestion of fronds may cause mild stomach upset but is not considered dangerous. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Australian Tree Fern care — frequently asked questions

What is the common name for Cyathea cooperi?

Cyathea cooperi is most commonly called Australian Tree Fern, but it is also known as Australian Tree Fern, Lacy Tree Fern, Cooper's Tree Fern. The names refer to the same species, so care instructions for Australian Tree Fern apply identically to anything sold as Lacy Tree Fern.

How much light does australian tree fern need?

Australian Tree Fern grows best in bright indirect light (just back from a sunny window). Grows in rainforest margins and tolerates more sun than most tree ferns. Bright, filtered light is ideal. In cooler climates, some morning direct sun is beneficial. In hot regions, protect from harsh afternoon sun, which scorches the delicate fronds.

How often should I water australian tree fern?

Water australian tree fern 2-3 times per week; increase in heat and wind. Keep roots consistently moist. The trunk should be kept damp — water it directly during dry spells. Fronds wilt rapidly when the plant dries out. In windy, hot conditions, water daily. Reduce in cool winter months. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is australian tree fern toxic to cats and dogs?

Australian Tree Fern is pet-safe. Cyathea cooperi is not listed as toxic by the ASPCA. True ferns in the Cyatheaceae family have no documented toxic principle to dogs or cats. Ingestion of fronds may cause mild stomach upset but is not considered dangerous.

What USDA hardiness zone does australian tree fern grow in?

Australian Tree Fern is rated for USDA zone 9-11 and RHS hardiness H2. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Australian Tree Fern deep-dive guides

Every aspect of australian tree fern care, each with its own calibrated guide:

Featured in these plant shortlists

Australian Tree Fern qualifies for 9 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Australian Tree Fern is also known as Australian Tree Fern, Lacy Tree Fern, and Cooper's Tree Fern.