Coral Bells, Alumroot, Coralbells, Alum Root 'Obsidian'


Family: Saxifragaceae (saks-ih-frag-AY-see-ee) (Info)
Genus: Heuchera (HEW-ker-a) (Info)
Cultivar: Obsidian
Additional cultivar information:(PP14836)
Hybridized by Heims
Registered or introduced: 2003
» View all varieties of Heucheras




12-18 in. (30-45 cm)


12-15 in. (30-38 cm)


USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

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

Bloom Color:

White/Near White

Bloom Time:

Late Spring/Early Summer




Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

By dividing the rootball

Seed Collecting:

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

Foliage Color:


Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Average Water Needs; Water regularly; do not overwater

Where to Grow:

Suitable for growing in containers


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

Kenai, Alaska

Denver, Colorado

Farmington, Connecticut

Old Lyme, Connecticut

Waterbury, Connecticut

Cordele, Georgia

Chicago, Illinois

Mount Prospect, Illinois

Plainfield, Illinois

Washington, Illinois

Russell, Kentucky

Haydenville, Massachusetts

Norton, Massachusetts

Plainwell, Michigan

Silver Lake, Minnesota

Litchfield, New Hampshire

Cape May Court House, New Jersey

Averill Park, New York

Southold, New York

Boone, North Carolina

Durham, North Carolina

Pekin, North Dakota

Cincinnati, Ohio

Coshocton, Ohio

Ravenna, Ohio

Enid, Oklahoma

Portland, Oregon

Norristown, Pennsylvania

Philadelphia, Pennsylvania

Conway, South Carolina

Memphis, Tennessee

South Jordan, Utah

Montpelier, Vermont

Alexandria, Virginia

Arlington, Washington

Bellevue, Washington (2 reports)

Kalama, Washington

Kirkland, Washington

Vancouver, Washington

show all

Gardeners' Notes:


On May 7, 2013, in2art from Bellevue, WA (Zone 8a) wrote:

This is the best performer of all the Heucheras I have. Stays evergreen in winter and looks like a small shrub in summer (5-10 times larger than the others). I grow it in full sun. If it starts to get leggy, mound some soil up on it (don't cover crown) and it will grow additional roots on stems, or break them off and pot them.


On Apr 28, 2011, donp17 from Arlington, VA wrote:

Incredible plant. I took a chance and put it in container on an east facing wall, and mostly no chance of getting other watering than rain.

It took our usual droughts as though it was in the sedum family. Some leaves persisted through the winter giving it some presence.

Now that it's Spring again, it's taken off.

Color is great all seasons.


On Oct 2, 2006, wickerparker from Chicago, IL (Zone 5b) wrote:

This heuchera has performed very well for me, in a number of spots with differing conditions. Holds its dark foliage color from spring till frost.


On Jun 7, 2006, pirl from (Arlene) Southold, NY (Zone 7a) wrote:

Love the depth of color! Well behaved in partial shade.


On Jul 29, 2005, franbo from Waterloo,
Canada wrote:

My three plants are in their second year. They have done well despite dry summers and cold (-30) winters in Ontario. This year the leaves are glossy purple-black and look stunning next to the Japanese Golden Grass (Hakonechloa macra Aureola)


On Jun 30, 2005, keno from Ottawa, ON (Zone 4a) wrote:

It has survived a tough Ottawa (Canada's capital) winter, i.e. zone 4a. It thrives again this spring. The foliage has a bit of green this year; possibly due to location not shady enough.
Despite its dark colour, it looks outstanding among other green perennials.


On Nov 23, 2004, esw from Haydenville, MA (Zone 5a) wrote:

Started out in my garden in a mostly sunny area and didn't like it. When moved to a morning, early afternoon sun and afternoon shade it perked up and is thriving. Deep dark unmarked foliage, somwhat shiny. Very striking planted near Heuchera 'Amber Waves' for contrast. Hardiness yet to be determined in my zone 5 garden...


On Oct 16, 2004, Kruch72 from Elgin, IL (Zone 5a) wrote:

Very nice foilage.