Tall Bearded Iris 'Midnight Oil'


Family: Iridaceae (eye-rid-AY-see-ee) (Info)
Genus: Iris (EYE-ris) (Info)
Cultivar: Midnight Oil
Hybridized by Keppel
Registered or introduced: 1997
» View all varieties of Iris


Tall Bearded (TB)


24-36 in. (60-90 cm)

36-48 in. (90-120 cm)


12-15 in. (30-38 cm)

15-18 in. (38-45 cm)

18-24 in. (45-60 cm)


USDA Zone 3a: to -39.9 C (-40 F)

USDA Zone 3b: to -37.2 C (-35 F)

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)

Sun Exposure:

Full Sun


Parts of plant are poisonous if ingested

Handling plant may cause skin irritation or allergic reaction

Bloom Color:

Dark Purple/Black

Bloom Time:

Midseason (M)



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 rhizomes, tubers, corms or bulbs (including offsets)

Seed Collecting:

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

Awards (if applicable):

Honorable Mention

Award of Merit

Walther Cup

Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Flowers are fragrant

Water Requirements:

Average Water Needs; Water regularly; do not overwater

Where to Grow:

Unknown - Tell us


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


Tucson, Arizona (2 reports)

Citrus, California

Emeryville, California

Gainesville, Georgia

Eastport, Idaho

Macy, Indiana

Hebron, Kentucky

Durham, Maine

Gladwin, Michigan

Marquette, Michigan

Robertsville, Missouri

Omaha, Nebraska

South Sioux City, Nebraska

Las Vegas, Nevada

Los Alamos, New Mexico

Lawton, Oklahoma

Gold Hill, Oregon

Greeneville, Tennessee

Pasco, Washington

Hustisford, Wisconsin

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Gardeners' Notes:


On Mar 8, 2012, lindypuddin from stony mountain, MB (Zone 3a) wrote:

planted this iris slightly shaded 2010 zone 3a

one word to describe ? stunning

i'm so careful with this plant....it's slightly raised from the soil, watered regularly, and fertilized in the early-spring and
early fall, i know 'they' say don't fertilize in fall...but i find in
this zone it helps the plants draw energy for winter.
i also leave dead foliage to form a mat over the plant, it keeps the moisture from rotting the rhizome.


On Jul 4, 2010, azulivines from Burnaby, BC (Zone 7b) wrote:

Huge, fragrant, and black. This is the only iris I would classify as black. The beard is fuzzy-purple which, at first, makes you think you've got one interesting caterpillar on your flowers.

Our absolutle favourite german iris by far!


On Jun 15, 2010, philljm from Hustisford, WI (Zone 5a) wrote:

This plant bloomed the first year, with gorgeous deep purple, almost black flowers. everyone that saw it raved about it. It is tall, bloomed around the 10th of June in south central Wisconsin, and I may stake it next year, a strong storm battered it down, but didn't harm it.


On Mar 19, 2006, Joan from Belfield, ND (Zone 4a) wrote:

Awards: American Iris Society Honorable Mention 2000; Walther Cup 2000; Award of Merit 2002


On Feb 18, 2006, TBGDN from (Zone 5a) wrote:

MIDNIGHT OIL: (Keith Keppel, R. 1997). Sdlg. 91-174A. TB 36" (91 cm) M. "Black self, darker than eggplant (M&P 48-H-12), F. with slight velvet finish; style arms darker than port (56-E-12); beards grape (47-JL-12); slight sweet fragrance. 88-45C: ((Snowbrook x Blackout) x 84-93B, Light Show sib) X Before the Storm., Keppel 1998." The preceding data was researched from the American Iris Society. This is one of the 'blackest' irises I grow along with Anvil Of Darkness, Before The storm, and Obsidian. They don't come much darker than these. It bloomed the first year after planting for me on two stems with several buds. I was surprised a first year iris would send up two bloom stalks! I'm very positive about this one as it seems to have a more refined form and ruffles than other blacks. Seems ... read more


On Mar 15, 2005, doss from Stanford, CA (Zone 9b) wrote:

(Keppel, 97) Mid season bloomer. 36" Fragrant
"Fine black self with grape beards. Exceptional grower with excellent branching and nice ruffles." This Iris was awarded the American Iris Society Honorable Mention '00; and the Award of Merit '02.
Note from Cooley's Iris Gardens


On Jun 8, 2003, mountaineer from Manhattan, KS wrote:

This iris has done very well for me. It blooms late in zone 5. It is probably the closest to a black iris that I have seen. Very velvety and beautiful