Sphaeropteris Species, Norfolk Island Tree Fern, Norfolk Tree Fern, Smooth Tree Fern

Sphaeropteris excelsa

Family: Cyatheaceae
Genus: Sphaeropteris (sfay-ROP-teris) (Info)
Species: excelsa (ek-SEL-suh) (Info)
Synonym:Alsophila excelsa
Synonym:Cyathea brownii


Tropicals and Tender Perennials


Water Requirements:

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

Sun Exposure:

Sun to Partial Shade

Light Shade

Partial to Full Shade


Grown for foliage


Foliage Color:

Unknown - Tell us


15-20 ft. (4.7-6 m)

20-30 ft. (6-9 m)

30-40 ft. (9-12 m)

over 40 ft. (12 m)


8-10 ft. (2.4-3 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)

Where to Grow:

Unknown - Tell us


Unknown - Tell us

Bloom Color:


Bloom Characteristics:

Unknown - Tell us

Bloom Size:

Unknown - Tell us

Bloom Time:


Other details:

Soil pH requirements:

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

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

Fairfield, Iowa

Gardeners' Notes:


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

Cyathea brownii is reputed to be the largest living species of tree fern, and can attain a height of over 40 feet.

It is listed in the 1997 IUCN Red List of Threatened Plants as vulnerable.

Available from Thimble Farms, B.C., Canada.

Cyathea are listed on CITES Appendix II.


On Sep 24, 2005, BayAreaTropics from Hayward, CA wrote:

It is also a much darker green than the Australian tree fern when grown in light shade. Hard to find..got mine at a botanical garden sale. It has grown from a seedling (frondling?) to 6 foot spread in 4 years-and only two of those in ground. And it does like fertilizer more than the common tree ferns.Yet,still does not develop the massive trunk as it does in it's natural habitat. And i have noticed that for a large fern it has a tendency to only send up only one frond at a time.
EDIT: Sailed through the 07 freeze. It even threw out a frond or two over the winter-well,the second frond is still a crozier. But,I'm not so sure i would call it a fast growing tree fern.
EDIT2: After a slowing down period it has taken off again. Even the crown seems to be too large for the trunk t... read more


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

For those who love tree ferns, but can't wait for your Australian tree fern to get to any size, or shade your yard, this is the fern for you (one of several). This is 3x as fast a grower, and larger and better looking than an Australian tree fern (Cyathea cooperi), except for the Brentwood variety- that one is faster and larger still. This has a darker trunk and slightly more sun tolerance. However, full sun is only recommended in moderately cooler climates. Blazing heat, like seen inland in Southern California, will toast any tree fern. Then shade is recommended.