Black Tree Fern, Korau, Mamaku, Sago Fern

Cyathea medullaris

Family: Cyatheaceae
Genus: Cyathea (sigh-ATH-ee-uh) (Info)
Species: medullaris (med-yoo-LAIR-iss) (Info)
Synonym:Sphaeropteris medullaris
Synonym:Cyathea affinis
Synonym:Polypodium medullare


Tropicals and Tender Perennials


Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Requires consistently moist soil; do not let dry out between waterings

Where to Grow:

Unknown - Tell us


20-30 ft. (6-9 m)

30-40 ft. (9-12 m)

over 40 ft. (12 m)


10-12 ft. (3-3.6 m)

12-15 ft. (3.6-4.7 m)


USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

USDA Zone 11: above 4.5 C (40 F)

Sun Exposure:

Sun to Partial Shade

Light Shade

Partial to Full Shade



Bloom Color:


Bloom Time:



Grown for foliage


Other details:

This plant may be considered a protected species; check before digging or gathering seeds

Soil pH requirements:

6.6 to 7.5 (neutral)

Patent Information:


Propagation Methods:

From spores

Seed Collecting:

N/A: plant does not set seed, flowers are sterile, or plants will not come true from seed


This plant has been said to grow in the following regions:

Encino, California

Hayward, California

San Francisco, California

San Leandro, California

Santa Barbara, California

Naples, Florida

show all

Gardeners' Notes:


On Jul 13, 2009, DaveH from San Francisco, CA (Zone 10a) wrote:

Cyathea medullaris is a stunningly attractive tree fern. In San Francisco it is very fast growing. The one in my garden grew from 4 ft high to 15 ft high and 15 ft wide in only 3 years!


On Nov 14, 2007, albey30 from Christchurch,
New Zealand (Zone 9a) wrote:

Cyathea medullaris leaves die back completely at approx -4.0 degrees celcius. I live in zone 9a - 9b ( -5.0 degrees minimum, in New Zealand where this is native to this country, and the leaves on both my Cyathea medullaris die back completely. They grow back in the spring. But in warmer parts of New Zealand the leaves survive the winter. New Zealands climate zones range from approx: 8a -10b, with low heat zones of: 1 - 3.


On May 7, 2007, Cretaceous from El Sobrante, CA (Zone 9b) wrote:

Cyathea medullaris is native to Fiji, Tahiti, and New Zealand.

Cyathea are listed on CITES Appendix II.


On Sep 12, 2005, BayAreaTropics from Hayward, CA wrote:

Without a doubt the greatest tree fern in cultivation.Both in looks and size and also a i feel a very fast grower for frost free cooler climates on the west coast. The higher humidity allowing it to thrive. And as it grows in Fiji It can take tropical heat if,again,humidity is high. There are two forms of this fern in the trade- the more desirable black and the still large green stipe form. MAKE SURE you ask if ordering them. You might be disappointed with the blander green as seen in Pam Bobs photo in Manhattan Beach ca.
Hardy to about the mid 20's..sometimes lower if large and protected.New Zealand medullaris have taken ice and snow.NEVER allow to go dry,regular acid fertilizer,and protect from high wind. The more trunk it gets,the more water it will need. Try to plant away from ... read more


On Aug 24, 2003, palmbob from Acton, CA (Zone 8b) wrote:

ANother great tree fern for So Cal, but not a fast grower. Also hard to find large, so only small seedlings usually available. This is a biggy, though, and there are many mature examples of this tree in So Cal with over 20' of trunk. It is a great specimen tree with attractive, droopy leaves and tall, sturdy trunks. The trunk color is somewhat blackish from the hairs growing on it. This is a native of New Zealand, where many thousands of spectacular examples can be seen. There it needs full sun, but here in So Cal full sun can sometimes be hard on it. These tall tree ferns can sometimes be hard to keep happy once they get a lot of trunk. The trunk is really a modified root system and benefits greatly from being moistened frequently. Some do best if a drip system is applied to the ... read more