Growers bring new options to market, help drive a new environmental ethic

Many factors influence shade tree trends, but growers themselves are one of the most significant. 

“To a certain extent, trends are driven by growers,” said Amy Whitworth, owner of Plan-It Earth Design, a landscape design firm based in Portland, Oregon. “[That’s] because no matter what is ‘hot’ online or in print, if you can’t get it, you’re going to come home with something that is in stock.”

It’s not as if tree growers are waiting to find out what people want. So, if it’s a two-way street and trends are created by growers, then the choices growers make now will shape the trends of the future. They influence the cultural shifts of buying habits, according to Nicholas Staddon, plantsman and company spokesman with Everde Growers, a large wholesale grower based in Orange, California, with farms in multiple states. 

Growers reported that more and more consumers are asking for landscape diversity, habitat, songbird and insect pollinator values, and other attributes. Mark Krautmann, owner of Heritage Seedlings and Liners in Salem, Oregon, said that ecosystem stewardship should be foremost among the values guiding the green industry. 

“Stewardship requires husbandry, our advocacy and commitment to our personal part of the urban forest, and growing the right plants for specific sites,” he said. “Moreover, thoughtful design — an attractive integration of both natives and introduced ornamentals — can reduce our maintenance costs and give us a sense of ownership of habitat values when the natural world begs our active commitment to its robust health.” 

For many years, Nancy Buley, director of communications at wholesale tree breeder and grower J. Frank Schmidt & Son Co. in Boring, Oregon, has pushed the message that trees provide ecosystem services. She has noticed that this message is finally getting through now. 

“The general public, consumers, are finally hearing the message that trees are essential to our health and well-being,” she said. “They clean the air, produce oxygen, sequester carbon, cool our cities, reduce the heat island effect and improve mental health.” 

This information has been out there for years, but people are taking greater notice, she said. 

“People are finally seeing that climate change is real, and it’s happening here in our own back yards, and affecting us — wildfires, hurricanes, heat domes, torrential rains and floods, sea rise,” Buley said. “People have learned that planting trees can help to mitigate some of the damage that we’ve done to our planet. And planting trees is something that just about everyone can do.”

In a prior installment regarding shade tree trends, published in the August issue of Digger, we talked about flowering shade tree trends. This time, we will discuss shade trees that don’t necessarily have prominent flowers, from Acer to Zelkova, and we’ll also include some columnar and native options.

Acer

Japanese maples (Acer palmatum) have never stopped trending in Whitworth’s memory, especially as there are so varieties and colors to choose from.

“I think it is definitely a tree that homeowners know,” she said. “It’s a requested tree. The red ones continue to be popular because they are different. But a lot of people have been living with them with verticillium wilt, but the homeowner doesn’t necessarily know that. There are a lot of maples in the urban forest, and we don’t need more maples, I try not to put more than one on the property.”

Eric Prescott is the manager at nursery retailer Farmington Gardens in Beaverton and Hillsboro, Oregon, which shares ownership with wholesaler Eshraghi Nurseries in Beaverton. “We grow lots of Japanese maple,” he said “‘Mikawa yatsubusa’ is the top tree.” 

Its dwarf stature — growing to 5 feet in 15 years — brings fall color in a heat tolerant plant to the patio area, as it can be grown in a container or a display garden. The unique overlapping leaves give it a bonsai affect. In 2015, it was award “Maple of the Year” by the North American branch of the Maple Society.

Coral bark Japanese maple (A.p. ‘Sango-kaku’, 20–25 feet tall by 15–20 feet wide, Zones 5–8) has been around for a while. Rose Potter, tree and shrub buyer at Farmington Gardens, believes it stays trending for its easy care, narrower and upright canopy and bright red bark that intensifies in color as temperatures dip 

For the larger leaf maples, customers are gravitating to Pacific Sunset^® maple (A. truncatum × A.p. ‘Warrenred’ PP7433, to Zone 4b) and Urban Sunset^® maple (A.t. × A.p. ‘JFS-KW187’ 27545, to Zone 5) maples.

“People are still wanting maples, even if they’re no longer a street tree,” Potter said. “They are a nice backyard tree for a medium lot and for nice color.”

Both varieties are adaptable to heat and drought conditions. Pacific Sunset has dark glossy leaves, vibrant orange to red fall color, and matures with a rounded crown on 30 feet tall by 25 feet wide tree. Urban Sunset grows fast but tops out at 35 feet tall and a narrow, pyramidal to oval 20-foot spread.

Although introduced in 2006, Buley puts Redpointe^® maple (A. rubrum ‘Frank Jr.’ PP16769, 45 feet tall by 30 feet wide, Zone 5) as a still trending tree. 

“It’s a popular seller in both commercial markets and garden centers, to homeowners,” she said. Because it is so very adaptable, has the distinct red fall color and has a nice broadly pyramidal shape with a strong dominant central leader. 

There are more columnar ones coming out in the future.“We note a strong interest in grafted Japanese maples, which is a bit of a surprise, since they’re grown in such abundance,” Krautmann said. “But they fit so flexibly in small yards.” 

The primary A.p. varieties Krautmann sees trending are the red uprights — such as ‘Bloodgood, ‘Fireglow’ and ‘Emperor 1’ — and laceleafs such as ‘Tamukeyama’ or ‘Inaba Shidare’. Other red cultivars that are rising in popularity include the narrow-formed and slow-growing ‘Twombly’s Red Sentinel’ (15 feet tall by 6–8 feet wide; Zones 5–8) and the globe-shaped ‘Moonfire’ (20 feet tall and wide; Zone 5b). 

Columnar trees

“We can’t grow columnar trees fast enough to meet current demand,” Buley said. “They’ve been popular for a long time, but now more than ever are: Streetspire^® Oak, Beacon^® Oak, Armstrong Gold^® Maple, Raspberry Spear^® and Ivory Spear^® crabapples.”

Thinner plants that take up less of a footprint are the hit of the trend. There are new releases, and then growers are going with the narrower forms of old favorites, according to Whitworth.

These trees check the boxes related to other categories, like the desire for more diversity (the oaks), the continued search for fall colors and better disease resistance. 

“Streetspire was selected for its resistance to powdery mildew and anthracnose, which tends to be an issue in the seedling,” Buley said.

In backyard renovations going on, Prescott sees homeowners leaning toward small columnar trees like Armstrong Gold^® (A.r. ‘JFS-KW78’ PP25301; 40 feet tall by 12 feet wide; Zone 4) 

Expanding from maples, Whitworth calls out Carpinus betulus ‘Frans Fontaine’ and Black Tower Elderberry (Sambucus nigra ‘Eiffel01’) as the narrow, columnar counterpart to wider trees. 

Upright European hornbeam (Carpinus betulus ‘Fastigiata’) is always a trending tree — especially as a street tree, Potter said. It’s nicely shaped, densely branched “and doesn’t drop stuff.”

“The trend for smaller oak leads to some terrific fastigiate oaks that are upright and much better behaved,” Staddon said. Crimson Spire™ (Quercus robur × Q. alba ‘Crimschmidt’, 40–45 feet tall by 15–20 feet wide; Zones 5–9), which is drought tolerant, adaptive to many soils and disease resistant. 

“Basically, any columnar trees, if there is a new one of that that comes out, we try to pick it up pretty quick,” Brentano said. Liquidambar styraciflua ‘Slender Silhouette’ (35–50 feet tall by 4 feet wide, Zones 5–8) is a good example.

“Another Eastern U.S. native that merits wider use is Carpinus caroliniana,” Krautmann said. “Several firms have introduced new varieties that are more diminutive in mature size or columnar in shape as compared to common seedlings.

“A reasonable option that combines both attractive price and brilliant fall color advantages, the Wisconsin Red™ seedling strain offers consistently red, orange and yellow autumn leaves that set them apart from run-of-the-mill seedlings,” Krautmann said .

Carpinus is one of Krautmann’s favorite genera. 

C. betulus ‘Columnaris Nana’ (Zones 4–8) is a compact, neatly upright semi-dwarf reaching up to 20 feet in as many years. 

“It’s tidy and not fussy if grown in a light container mix,” he said. “You can stick it in a pot and let it grow there for a few years on a patio or deck. It’s so formally attractive, with zero pruning care.”

Krautmann also points to a new hybrid hornbeam, Skylark™ (C. × ‘Shelby’, 25–35 feet tall by 10–15 feet wide, Zones 5–8), introduced by The Morton Arboretum via Heritage Seedlings, that combines the ease of care of C.b. ‘Fastigiata’ with the hardiness of C.c. 

“It’s an excellent street tree candidate,” he said.

“Another charming, unusual hornbeam that always elicits a ‘What’s that?’ response is Japanese Hornbeam (Carpinus japonica),” Krautmann said. “It’s of globe form to 20 feet, with singularly beautiful sawtooth leaves and charming hanging fruits. They’re hop-like in character and dangle beneath the foliage as if the tree were decorated. We’ve seen a steady, if modest, bump in demand for this taxon and its Korean cousin, Carpinus coreana, with much smaller leaves, slower growth to 15 feet, and a bit better drought tolerance. Both are suitable for specimen use in small landscapes; neither is fussy.”

Zelkova

Overall, Zelkova are riding the trend and in high demand. 

JFS’s City Sprite^® Zelkova (Zelkova serrata ‘JFS-KW1’ PP20996) has a compact oval shape, keeping trim at 24 feet tall by 18 feet wide. It has a low maintenance habit and good fall color. City Sprite is a smaller version of the larger statured species and matures at a lower rate. 

“It has really caught on, and the older it gets, the more we see just how nice it is,” Buley said. 

These improved cultivars are in high demand, as evidenced by JFS’s 2022 introduction of the slightly larger Zileration™ zelkova (Zelkova serrata ‘JFS KW4ZS’ P.A.F., 24 feet tall by 18 feet wide). 

“It got snapped right up, first offering,” Buley said. They are expected to continue trending up. 

Native trees

“Oregon native trees and pollinator-friendly trees continue to be really big,” Whitworth said. She lends attention to cascara (Rhamnus purshiana, 25 feet high by 20 feet wide) in the Pacific Northwest as it is a reasonably sized native tree for smaller spaces.

There are native selections of vine maple with interesting traits, including Acer circinatum ‘Pacific Fire’ with red stems, A.c. ‘Burgundy Jewel’ with purple leaves, and blooming serviceberry (Amelanchier alnifolia) with a short and narrow stature (4–15 feet by 6–18 feet).

“The native plant movement is influencing our efforts to develop cultivars of native trees,” Buley said.

In cities, there is a definite trend toward a preference for native trees in urban forests. “[It can be problematic] because there is nothing natural or ‘native’ about most urban planting sites,” Buley said. “The benefit of cultivars is that you have predictable shape and performance. Bur oak (Quercus macrocarpa) can be all over the map when grown from seed.” 

There’s a place for unpredictability, but when trying to put an oak in a certain urban space, it’s good to know how it will perform and what shape it will take before planting.

That said, native oaks are trending up — bur, chinkapin, chestnut, swamp white oak.

“A lot of them are quite suitable for urban use, and depending on how they evolve, they can handle more pH.” Buley said. “Oaks are long lived and have good storm resistance, and good branching, and they are generally hard workers — durable and long-lived, although not many are in commerce, for a variety of reasons.”

Urban foresters are asking for chinkapin and chestnut oak, but they are not used much. Instead, it leads to a chicken-or-the-egg situation: “If we grow them, people will specify them, and there will be trees there when people want them,” Buley said. “But it’s complicated to have the tree supply there. For instance, with chestnut oak, we haven’t grown them for a long time and there are not very many, but they have nice orange colors.”

As part of the native trend, Farmington Gardens has been selling a lot of Populus tremuloides (quaking aspen). Customers see the white bark, and they want it. 

Although drought tolerant trees of any kind are huge, the demand by homeowners for manzanitas is “off the charts,” according to Whitworth.