Cass County Extension
Woody Plants for Trial Use
|Woody Plants which are borderline
in hardiness (subject to winter injury) or questionable in adaptability to the North
Dakota environment. However, some of these plants have been established in better than
average sites. None of them can be recommended for general planting throughout North
Adam's Needle - Yucca filamentosa (Y. glauca, yucca or soapweed, is native and hardy)
Apple, Dwarf - Malus grown on EM & MN rootstocks (should be mulched for winter protection).
Ash, Blue - Fraxinus quadrangulata
Ash, White - Fraxinus americana and all cultivars to date except for `Autumn Blaze' and ` Northern Blaze (hardiest) which are sufficiently winter hardy.
Autumn-Olive - Elaeagnus umbellata
Arborvitae, Sunkist - Thuja occidentalis Sunkist and other golden-yellow cultivars (subject to winter burn)
Azalea (Deciduous types) - Rhododendron University of Minnesota Northern Lights Hybrid series & Mollis Hybrid Azalea Rhododendron kosterianum
Barberry, Redleaf Japanese - Berberis thunbergii `Atropurpurea' and numerous other purplish-red leaved cultivars (may freeze back). Emerald Carousel Barberry is fully hardy
Barberry, Yellow - Berberis thunbergii `Aurea' and other yellow/gold leafed cultivars (usually lack winter hardiness)
Birch, River - Betula nigra and cultivars
Bittersweet, Chinese and Loesener - Celastrus orbicultus and C. loeseneri
Boxwood, Littleleaf (Korean) - Buxus microphylla and cultivars (winter drying and burning may be a problem)
Buckthorn, Columnar - Rhamnus frangula and cultivar Tallhedge
Burning Bush, Dwarf - Euonymus alata compacta
Bush-honeysuckle - Diervilla X splendens (Dwarf Bush-honeysuckle is hardy)
Catalpa, Northern - Catalpa speciosa
Clematis, Sweetautumn - Clematis terniflora (syn. C. maximowicziana and C. paniculata)
Corktree, Macho - Phellodendron amurense Macho (species is hardier)
Daphne - Daphne X burkwoodii and cultivars (Rose Daphne is hardy)
Dogwood, Kelsey Dwarf - Cornus sericea `Kelsey'
Dogwood, Pagoda - Cornus alternifolia (drought causes dieback; not well adapted tp our area)
Euonymus (Spindle tree), European - Euonymus europaea and cultivars
Euonymus, Wintercreeper - Euonymus fortunei and cultivars
Fir, White - Abies concolor (not as well adapted as Balsam Fir; winter burn common)
Forsythia, Border - Forsythia X intermedia & cultivars (new clones and/or hybrids of F. ovata, Early Forsythia and F. europaea, Albanian Forsythia are winter hardy including flower buds a majority of the winters) e.g. `Meadowlark', `Northern Gold' and `Northern Sun'
Ginkgo (Maidenhair tree) - Ginkgo biloba and cultivars
Hemlock - Tsuga species and cultivars (needs cool acidic soul and adequate moisture)
Holly-grape, Creeping - Mahonia repens
Holly-grape, Oregon - Mahonia aquifolium and cultivars
Honey-locust - Gleditsia triacanthos & most cultivars. `Imperial' and `Skyline' are regarded as two of the hardier cultivars; `Prairie Silk is considered hardy
Honeysuckle, Emerald Mound - Lonicera xylosteum `Emerald Mound (Claveys Dwarf and Miniglobe are hardy)
Honeysuckle, Goldflame - Lonicera X heckrotti
Honeysuckle, Trumpet - Lonicera sempervirens and cultivars
Hydrangea, French or Bigleaf - Hydrangea macrophylla and cultivars including `All Summers Beauty, Nikko Blue and Pink Elf
Juniper, Chinese - Juniperus chinensis Numerous cultivars of Chinese Juniper have proven to be borderline in hardiness in North Dakota, e.g., `Armstrongii', `Blaauw', `Blue and Gold', `Blue Point', `Fairview', `Fruitlandii', `Gold Star', `Hetzii', `Hetzii glauca', `Kaiuzuka', `Kateleeri', `Mordigan', `Old Gold', `Robusta Green', `Sea Spray' and `Spartan'. `Golden Pfitzer is the hardiest of the gold types.
Locust, Black - Robinia pseudoacacia and cultivars. `Ruby Lace' is not hardy.
Maple, Norway - Acer platanoides and cultivars. Commonly planted in this area but are not totally hardy. `Emerald Lustre' is the most adapted. Purple-red leafed cultivars such as `Crimson King', `Royal Red' and `Schwederli' are especially popular and scattered established plants can be found throughout the area.
Maple, Red - Acer rubrum and cultivars. Poor performance due to low moisture and alkaline soils. New cultivars from Northern Minnesota seed sources are showing improved adaptability, e.g., `Autumn Spire, `Firedance', `Northfire' and `Northwood'.
Maple, Purpleblow - Acer truncatum and hybrid cultivars
Maple, Sugar - Acer saccharum and cultivars. Poor performance due to low moisture and alkaline soils. `Green Mountain is one to try.
Maple, Sycamore - Acer pseudoplatanus and cultivars
Mockorange, Miniature Snowflake - Philadelphus Miniature Snowflake
Mountain-ash, Korean - Sorbus alnifolia
Oak, English - Quercus robur and cultivars
Oak, Pin - Quercus palustris and cultivars (poor performance due to low moisture and alkaline soils)
Oak, Red - Quercus rubra (poor performance due to low moisture and alkaline soils)
Oak, Swamp White - Quercus bicolor (poor performance due to low moisture and alkaline soils)
Pine, Austrian - Pinus nigra (winter burn can be a serious problem)
Pine, Bristlecone - Pinus aristata (often winterburns)
Pine, Jack - Pinus banksiana (not well adapted here)
Pine, Red - Pinus resinosa and cultivars (not well adapted here)
Pine, White - Pinus strobus and cultivars (not well adapted here; winter burn)
Planetree, American (Sycamore) - Platanus occidentalis
Rhododendron, Haaga - Rhododendron `Haaga and other Marjatta Hybrids
Rhododendron, PJM - Rhododendron X 'PJM' (hardy but root rot is a problem in heavy wet soils)
Rose - Rosa Hybrid cultivars (Floribunda, Grandiflora, Hybrid Tea, Climber types)
Shrub Roses - Rosa Hybrid cultivars including the David Austin series, some of the Explorer series, the Meidiland series, Buck roses and numerous other cultivars. The Parkland series as well as some of the Explorer series are hardy. Many of the Rugosa Roses are also hardy.
Smokebush - Cotinus species and cultivars (commonly sold in this area; kills back to the ground each winter) Purple leafed cultivars are less hardy than species.
Spirea, Bridalwreath - Spiraea prunifolia
Spirea, Snowmound - Spiraea nipponica Snowmound (`Halwards Silver is slightly hardier)
Spruce, Black - Picea mariana (poor performance due to low moisture and alkaline soils)
Spruce Dwarf Alberta - Picea glauca `Conica (may winter burn badly)
Spruce, Serbian - Picea omorika (winter burn may be a problem)
Sumac, Staghorn - Rhus typhina and cultivars (winter freeze back is common)
Sycamore (American Planetree) - Platanus occidentalis
Trumpet Vine - Campsis radicans and cultivars (freezes to the ground each winter)
Weigela - Weigela species and cultivars (Variegated Weigela is less hardy)
Willow, Austree - Salix alba x Salix matsudana hybrid (winter dieback especially after dry season)
Willow, Babylon Weeping - Salix babylonica
Willow, Corkscrew - Salix matsudana `Tortuosa' ( Hybrids: `Golden Curls and `Scarlet Curls are hardier)
Willow, Dwarf Blue Leaf Arctic - Salix purpurea Nana (summer and winter desiccation dieback) Compact Purple (Slender Purple Osier) Willow does better here.
Willow, French Pussy (Goat) - Salix caprea . Daphne Willow is a much better choice.
Willow, Japanese Fantail - Salix sachalinensis Sekka
Willow, Niobe Weeping - Salix alba `Tristis (sunscald and winter dieback can be a problem)
Willow, Nishiki - Salix integra `Hakuro Nishiki
Willow, Wisconsin Weeping - Salix X blanda (not as hardy as Niobe Weeping Willow)
Wintercreeper Euonymus - Euonymus fortunei and cultivars
Wisteria - Wisteria species and cultivars
Witchhazel - Hamamelis species and cultivars
Woadwaxen, Royal Gold - Genista tinctoria Royal Gold
Yew - Taxus species and cultivars. The following cultivars have shown the greatest degree of hardiness in the Northern Plains: Taxus cuspidata `Cross Spreading', Taxus x media `Dark Green Spreader' and Taxux x media `Tauntonii' (best). Pyramidal forms are not reliably hardy.
|Todd Weinmann, Extension Horticulturist & Master Gardener Coordinator|
|Phone: (701) 241-5707|
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