The times are a changin’, and so is the climate. Tree planting, then, must also change if urban forests are to adapt to the uncertainties of our future weather. Are you still specifying your favorite trees from years ago? Then maybe it’s time to revisit your current selections with an eye toward optimum resiliency. Developing such climate-resilient trees is a top priority of the plant development program at J. Frank Schmidt & Son Co., a wholesale tree grower in Boring, OR.
As a leading developer and introducer of new and improved cultivars of shade and flowering trees, J. Frank Schmidt & Son Co. must always look to the future in our efforts to select trees that will survive and thrive in challenging, changing environments. Successes over the past 50 years of plant development have included the introduction or co-introduction of more than 100 improved tree cultivars, most of which remain in the trade today. (The best known of these is Red Sunset® Maple, introduced in 1966 and still a top choice among red maples.)
As J. Frank Schmidt prepares to celebrate 75 years in the tree business and plans for the future, our top goals for developing trees for modern landscapes include selecting varieties for heat, drought, and cold tolerance; low water requirements, low maintenance needs, and adaptability to varied soils and growing conditions. We are also always on the lookout for trees that are naturally pest and disease resistant in order to decrease, or hopefully eliminate, the need for chemical applications in the landscape.
Market trends also reveal an increasing demand for native trees that will help to support birds, pollinators, and wildlife. Yet planting natives can be challenging for landscape maintenance, as native trees often fail to thrive in urban settings, which are often vastly different from their native habitat. As a result, we’ve developed and introduced a line of native tree cultivars that can still deliver predictable performance, appearance, mature size, improved disease resistance, and adaptability to urban growing conditions.
With shrinking urban green spaces, columnar and small stature trees are also increasingly in demand. We have recently introduced several slender oaks, a columnar Hackberry, tightly columnar ornamental crabapples, and a petite Zelkova. Since landscapers must often specify trees for the planting strip between sidewalk and street and beneath utility lines, we considered this growing need in our UtiliTrees™ product line of small, upright-growing trees that are a good fit for that confined space. They also work well in small space gardens, courtyards, and terraces.
When specifying trees, planting for diversity should be a top priority. History tells us that diversity is key to achieving urban forest health and longevity. Chestnut blight, Dutch Elm Disease, Asian Longhorn beetle, and Emerald Ash Borer are among the diseases and insects that have wiped out billions of trees in our forests and cultivated landscapes. Landscape designers and contractors can do their part to prevent catastrophic loss of landscape trees by specifying and planting a wide variety of trees of different genus and species rather than relying on a traditional or uniform plant palette.
There are lots of options out there: Be creative by subbing a cultivar of Gymnocladus dioicus, Espresso™ Kentucky Coffee Tree, for the widely-planted Honeylocust (Gleditsia triacanthos). Their arching branches, compound leaves and filtered shade are similar. Try the new Nyssa sylvatica cultivars (Firestarter®, Afterburner® Red Rage® and Green Gable® are examples) for fall color that rivals the brilliance of the popular and widely planted red maples. Choose Crimson Sunset® Maple over the widely planted Crimson King Maple for a similar “look” that offers improved resistance to heat, drought, and cold.
Top Tree Picks
Of course, it’s always helpful and time saving to have specific recommendations. Here are a few of our top picks in various categories:
Climate resilient trees. Climate-resilient trees perform well over a wide geographical area with varied weather conditions. One path to developing new and improved cultivars is to select trees grown from seed collected in hot, arid climates. Another is to hybridize compatible species and select for the best performers. Here are some adaptable, heat and drought tolerant examples.
Emerald Avenue® Hornbeam (Carpinus betulus ‘JFS-KW1CB’) has superior heat and drought tolerance, thanks to having originated in the southernmost range of European Hornbeam. When other cultivars of this species look tired and heat stressed during the dog days of summer, this one maintains healthy deep green foliage. Handsomely corrugated leaves are strongly textured, durable, and pest and disease resistant. Foliage is buttery yellow in autumn. Its strong trunk, dominant central leader, and sturdy branch arrangement make it well suited for use as a street and park tree. Broadly pyramidal to oval in shape, it grows to approximately 40’ tall and 28’ wide.
Emerald Sunshine® Elm (Ulmus propinqua ‘JFS-Bieberich) foliage is strongly textured, emerging with red tints and maturing to deep, rich green. Resistant to Dutch Elm Disease and Phloem Necrosis, it also resists the feeding of elm leaf beetles. Originating from seed collected in a rugged, arid region of China, it was selected as the best performer among seedlings grown out on the arid plains of western Oklahoma. A tough performer in urban settings, its mature height and spread is approximately 30’ tall x 25’ wide.
Redpointe® Maple (Acer rubrum ‘Frank Jr.’) has proven so adaptable since its introduction in 2006 that it has become our best-selling tree. Quickly embraced by our customers as “a grower’s tree,” its strong central leader and upright, symmetrical and balanced growth habit make it an easy-care tree in the nursery and a low maintenance tree in the landscape. Tolerance of heat, drought and higher pH soils add to its resilient character.
Crimson Sunset® Maple (Acer truncatum x A. platanoides ‘JFS-KW2) flourishes in hot and humid climates where most purple-foliaged trees fail to thrive. Dramatic purple leaves are drought and heat tolerant, retaining their dark, glossy color through the growing season. Foliage resists the leaf tatter and scorch damage of late summer that typically disfigures other purple-leafed maples and deepens to rich red-bronze in autumn.
This medium size shade tree is perfectly shaped for street tree use, and compact enough for shading today’s home landscapes and streetscapes. Unlike the popular and widely planted Crimson King Maple, its scorch-resistant leaves stay fresh and bright in late summer. Heat tolerance and leaf quality are gained from its Chinese parent, Shantung Maple (Acer truncatum). Upright and symmetrical branch habit and a strong central leader inherited from its Norway Maple parent (Acer platanoides) make it easy to maintain.
Native trees. Examples of improved cultivars of native species include selections of Tulip Poplar and Swamp White Oak.
Emerald City® Tulip Tree (Liriodendron tulipifera ‘JFS-Oz’) is the perfect tree for shading yellow brick roads and city streets. Glossy, emerald green foliage turns to bright yellow in autumn. Tulip-like flowers are a springtime bonus that attract pollinators when they appear among distinctively darker green leaves. A strong central leader, predictably uniform growth habit and relatively compact form are additional attributes that distinguish it from the species and recommend it for landscape use.
American Dream® Oak (Quercus bicolor ‘JFS-KW12’) offers an upright, broadly pyramidal form, glossy green, anthracnose and mildew resistant leaves. Beacon® Oak (Q. bicolor ‘Bonnie and Mike’) is a columnar selection discovered by Dr. Michael Dirr and brought to us for trial and introduction.
Columnar and small stature trees.
Armstrong Gold® Maple (Acer rubrum ‘JFS-KW78’) improves greatly on its parent, Armstrong Maple, with brighter foliage color, greater foliage density, and a compact, less leggy growth habit. Selected from an evaluation of hundreds of seedlings of ‘Armstrong’, its improved columnar form recommends it for narrow sites.
Crimson Spire® Oak (Quercus robur x Q. alba ‘Crimschmidt’) endures the heat of summer with style. Widely adaptable to a broad range of soil types and climates, it tolerates heat and drought and has fresh-looking, dark green to bluish green summer foliage that is mildew resistant. Its reddish fall color and narrow growth habit combine to make a striking picture in autumn.
Streetspire® Oak (Quercus robur x alba ‘JFS-KW1QX) stands tall and slender in the narrowest of streetscapes. Dark green, mildew resistant leaves turn red in autumn before falling to reveal stiffly upright branches. While similar to Crimson Spire™, it does not hold its brown foliage through the winter. Wide crotch angles and short upsweeping branches create a storm-resistant structure. Both are excellent choices for street tree plantings and narrow sites, growing to approximately 45’ tall x 15’ wide.
City Sprite® Zelkova (Zelkova serrata ‘JFS-KW1’) has a compact growth habit that distinguishes this striking city tree. Short internodes contribute to its compact, dense, and semi-dwarf form, resulting is the perfect little tree for tight urban spaces. Oval to vase-shaped, it grows to a height of approximately 24’ tall x 18’ wide. Fine textured foliage is brighter green in summer than the leaves of typical Zelkova, and turns yellow in autumn.
Low maintenance and low-to-no chemical input. Choose well-grown trees with inherent good structure to minimize pruning and/or future problems. Choose trees that are naturally pest and disease resistant such as our flowering crabapples which boast excellent disease resistance developed during a 40-year breeding and selection program:
Royal Raindrops® Crabapple (Malus ‘JFS-KW5’) offers better resistance to foliage disease than other purple-foliaged crabapples. Magenta-pink flowers of spring are followed by unique, deeply cut leaves, and in fall by tiny, long-lasting purple fruits.
Sparkling Sprite® Crabapple (Malus ‘JFS-KW207’) forms a perfect, formal topiary head without pruning! Its naturally rounded, dense canopy brings a formal appearance to the landscape. Deep pink buds open to a profuse display of pink-rimmed white flowers that serve as magnets for honeybees and other pollinators. Exceptionally clean, green, disease-resistant foliage is complemented by tiny golden fruits that last into the winter months and provide food for hungry birds.
Pink Flair® Cherry (Prunus sargentii ‘JFS-KW-58’) has exceptionally clean, deep green foliage with built-in insect and disease resistance. Hardy through Zone 3b, its late bud break prevents freeze damage to tender flower buds. Successful plantings in Spartanburg, SC, and Fargo, ND, prove its adaptability to a wide swath of climate zones.
In the past, project managers, homeowners, and landscape designers have typically only considered beauty, or shade, or curb appeal when it comes to tree selection. Yet today, clients—whether residential or commercial—are on the lookout for trees that are easy care, have low water needs, possess improved pest and disease resistance, and will adapt to climate change and variable growing conditions.
Landscapers can contribute to a more resilient, adaptable urban forest by thinking beyond beauty and aesthetics. Visit local nurseries and ask, “What’s new?” Keep tabs on new tree introductions and give them a try. By learning the many benefits of trees and familiarizing yourself with new tree introductions, you can guide your customers in choosing the optimum trees for now and the future.
Buley is director of communications for J. Frank Schmidt & Son Co., wholesale tree growers of Boring, OR, where she has been “talking trees” for 26 years. Named a Lifetime Honorary member of the American Society of Landscape Architects in 2004, she is also a member of GardenComm and various nursery and arboricultural organizations. Buley earned a BA in Technical Journalism and Horticulture from Oregon State University and is a graduate of the Municipal Forestry Institute (MFI). A longtime member of the board of directors of Friends of Trees, Buley lives and gardens in Boring, beneath an ever-widening canopy of shade.
Do you have a comment? Share your thoughts in the Comments section below, or send an e-mail to the Editor at [email protected]