Fraxinus / Ash

fraxinus / ash

The Ash tree.  These are a common favorite of Northern regions.  Tolerant of cold, drought, and many other adverse conditions it is no wonder these were a chosen tree of many homestead yards and windbreaks in the 1930's here in North Dakota.  There is much to be appreciated about ash.  Their growth rate is medium to fast, they have an upward canopy that makes them a desirable yard tree.  Their canopy is not so dense that grass does not grow underneath them, nor do they have roots that rise with age and become a problem when mowing and maintaining a lawn.

Fraxinus americana ‘Jefwis’
Nobility® White Ash

Nobility® was selected for its vigor, cold hardiness and early, purple fall color. This cultivar maintains a central leader and an even distribution of branches in the oval-shaped canopy. New twig growth turns purple in late summer.
Nobility® is a seedless cultivar with only male flowers.

Height: 50 ft

Spread: 30 ft

Fall Color: Deep Purple to Mahogany

USDA Zone: 4 - 8

Tolerant of cold, drought, and many other adverse conditions it is no wonder these were a chosen tree of many homestead yards and windbreaks
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Mancana ash

Mancana ash

Fraxinus mandshurica 'Mancana'
Mancana (Manchurian) Ash

Introduced by the Morden Research Station in Manitoba, Canada, this male, seedless selection of Manchurian ash transplants easily, and is tolerant of both drought and excess moisture. A great xeriscape plant, it has no serious disease problems.

This graceful ash has a weeping appearance with a defined oval canopy when mature.  This cultivar is also male and therefore a seedless tree. 

Height: 40 - 50 ft

Spread: 20 - 25 ft

Fall Color: Yellow

USDA Zone: 3 - 6


fraxinus x 'northern treasure'
northern treasure ash

This hybrid ash is a controlled cross between the Black Ash (Fraxinus nigra) and the Manchurian or Mancana Ash.  Northern Treasure has attractive compound leaves that extend on average 13 inches in length 11 inches in width. The fall color is a solid yellow-orange color. Northern Treasure is a vigorous grower that has an upright growth habit and tends to retain a strong central leader.
This ash cultivar has limited seed production.

Height: 35 - 40 ft

Spread: 20 - 30 ft

Fall Color: Yellow

USDA Zone: 2 - 8

northern treasure ash

northern treasure ash


Fraxinus pennsylvanica 'Rugby'
prairie Spire® green ash

Introduced by NDSU, this seedless cultivar was selected for superior hardiness and survival in adverse prairie conditions. Narrow and erect in youth, it matures to a narrow pyramidal form excellent for urban use. The glossy foliage is deep green with golden fall color.
This green ash cultivar is also seedless.

Height: 50 - 60 ft

Spread: 20 - 30 ft

Fall Color: Yellow

USDA Zone: 3 - 7




Ash have many positives that make them a desirable yard and street tree.  The fact that most modern cultivars of ash are male has eliminated the issue of seeds littering our yards and parks.  Ash have relatively few disease issues to speak of.  They are a great cleanup tree in the fall.  Ash are one of the last trees to wake up in Spring, making them fairly immune to late frosts that can damage young leaves.  In addition to that one hard frost in the Fall causes most of the leaves to drop immediately.  One raking session and you're done.


Perhaps the largest challenge with Ash is that they are also susceptible to an insect infestation.  The infamous Emerald Ash Borer affects all Ash species.  There are currently no reported cases of Emerald Ash Borer in the Williston community but the threat moves closer each year.  There ARE systemic insecticides available to treat these trees.  As both Ash and Birch are wind pollinated there is no concern of killing plant pollinators such as bees when treating these trees for this disease.


The optimal pruning time for Ash trees is late winter and early spring before leaves emerge.

For more on identifying old wood and new wood see our page on care of woody plants.