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Early, Large-flowered Clematis
Clematis 'Ken Donson'

Family: Ranunculaceae (ra-nun-kew-LAY-see-ee) (Info)
Genus: Clematis (KLEM-uh-tiss) (Info)
Cultivar: Ken Donson
Hybridized by Pennell
Registered or introduced: 1962
» View all varieties of Clematis


Unknown - Tell us


8-10 ft. (2.4-3 m)


36-48 in. (90-120 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)

Bloom Color:


Flower Fragrance:

No fragrance

Bloom Shape:


Bloom Diameter:

Large - 5 to 8 inches (12 to 20 cm)

Bloom Time:

Mid Summer

Late Summer/Early Fall

Sun Exposure:

Full Sun

Other details:

Average Water Needs; Water regularly; do not overwater


Unknown - Tell us

Pruning Groups:

Group 2 - Repeat bloomers; prune immediately after flowering

Patent Information:

Unknown - Tell us

Propagation Methods:

Unknown - Tell us

Seed Collecting:

Unknown - Tell us


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

Menlo Park, California

South China, Maine

Belgium, Wisconsin

Gardeners' Notes:


On Apr 26, 2007, Twonewfs from Belgium, WI (Zone 5a) wrote:

This clematis is a stunner. The deep blue blooms are about 7 inches across and it bloomed prolifically in my garden last year (it's 3rd year). It was mowed to the ground by deer/bunnies its first year, came back nicely, and was again (sadly) mowed to the ground last fall. It has enormous buds coming from what's left and I think I now see new growth coming from the ground, so I'm sure it will rebound, although I doubt it will bloom as well as last year, since much of the blooming is on old wood. This is a class B pruning code clematis. I grow it with a William Dafphin climbing rose and they make a stunning combination.


On Sep 21, 2006, mystic from Ewing, KY (Zone 6a) wrote:

Received The Royal Horticultural Society, Award of Garden Merit (AGM) in 1993.


On Oct 10, 2004, elsie from Lafayette, NJ (Zone 6a) wrote:

This plant was blooming when I received it and I don't have any first hand knowledge of it.

The plant tag says to trim back in fall after hard frost or in spring before new growth appears.