Smart swaps for spring planning

People will always want pretty plants, but of late, there has also been a big push to propagate species that are more pollinator- and planet-friendly.

“It isn’t about good versus bad. It’s about making better planting decisions with what we know today,” said Matt Guthrie during a presentation at this summer’s Cultivate. He, along with Tim Fleischer, are assistant horticulturists for the City of Dublin, Ohio, and the podcast co-hosts of “Shrubby Buddies.”

The duo presented “The Dirty Dozen: Plants to Lose & What to Choose,” discussing plants they’ve seen a lot of in landscaping over the years. Many of them became popular for good reasons – most commonly, they were popular, tough and widely available, showed vigorous growth and featured lovely foliage.

However, the 12 plants they focused on “had invasive tendencies, were bad for wildlife and some just bad cultivation,” Fleischer said. “It could be a great plant, just in the wrong place. These plants are not evil, just ready for retirement.”

Dublin, Ohio straddles USDA Plant Hardiness Zones 6A and 6B, which extend from New England southwest to Kentucky, north to Michigan and westward into southern Colorado – a large part of the nation. The plants (and their replacements) noted below work best in the Buckeye State but similar options may be suitable for other states.

Fleischer commented, “Nothing we recommend is going to be a one-to-one replacement.”

Guthrie added, “Let’s focus on what we’re gaining instead of what we’re losing.”

Landscape Trees

• Norway maple

“They looked like heroes … until we watched them for 40 years,” Guthrie said. It was particularly popular because of its purple foliage (especially with the variety ‘Crimson King’) and the dense shade it provided. However, like every plant on the dirty dozen list, it is an ecological concern, is invasive, is overused and offers a “homely autumn color.” It is displacing sugar maples in the Northeast, which is a problem, especially for sugarmakers.

Better options offered up by the “Shrubby Buddies” were the Freeman maple, the red maple and the sugar maple; and for ‘Crimson King’ specifically, purple catalpa, purple beech, forest pansy redbud or smokebush.

• Sawtooth oak

Beloved for its fast growth rate, adaptability and being able to produce acorns at young age to feed wildlife, it was thought to be a good street tree. But it’s invasive, “weedy at the very least” and an abundance of acorns is bad for streets and urban areas.

Better options included the white oak, the red oak or any native oak.

“This tree is a bigger issue farther south,” Fleischer noted. “It’s just coming on the radar in Ohio.”

Shrubs

• Barberry

One of barberry’s biggest selling points is its dramatic foliage color. But per a study from UConn, it also can dramatically increase tick populations. Sitting low to the ground it also tends to be a trash collector.

Better options listed are ninebark, Diervilla (bush honeysuckle), smokebush and ‘Limeglow’ juniper.

• Burning bush

Guthrie called this troublemaker “the next Bradford pear.” People love its autumn color and its density for screening. But it is both invasive and overused.

Better options offered were oakleaf hydrangea, black or red chokeberry, sweetspire, witherod, nannyberry or maple leaf viburnum, Fothergilla, witch-hazel, smooth sumac and American hazelnut.

• Privet (Ligustrum)

With good screening, ease of pruning and a lovely scent, privet faces the same charges as others on the list: invasive, overused and of ecological concern.

Better options mentioned include Virginia sweetspire, inkberry, arrowwood viburnum, bayberry, arborvitae, Spiraea ‘Ogon,’ plum yew and sweetshrub.

Other Plants

• Bugleweed

Bugleweed boasts colorful foliage groundcover and dry shade tolerance. An invasive, though, it tends to thrive in lawns.

Better options: Sedges, foamflower, coral bells, lungwort, Siberian bugloss, randy beef grass, dwarf goat’s beard.

• Butterfly bush

The presenters admitted including this on their list “may ruffle some feathers.” It often disrupts butterfly behavior, distracting them from pollinating other plants (and even mating). It’s popular because it does attract butterflies and it featured large and colorful blooms. But it’s an ecological trap and it lacks the ability to host caterpillars.

Better options: Buttonbush, American beautyberry, coralberry, summersweet, Virginia sweetspire, milkweed, ironweed, aster, goldenrod and bee balm – anything showy and native.

• Sweet autumn Clematis

Popular and adaptable, sweet autumn Clematis can also cause structural damage. It establishes and spreads quickly, often undetected until it is too late.

Better options: Climbing hydrangea, large-flowered Clematis and American wisteria. Fleischer added, “Virgin’s bower is the native version [of this plant] – it’s perfect replacement.”

• Wintercreeper

Yes, it has colorful foliage, but it’s also an ecological concern, invasive and overused.

Better options: Liriope (lilyturf), groundcover junipers, creeping phlox, fragrant sumac, dwarf ninebarks and Japanese forest grass.

• English ivy/periwinkle/Japanese Pachysandra

These three were grouped together because they are popular, tough, widely available, act as weed barriers, offer instant groundcover and have shade tolerance. But they’re also invasive and overused. “We don’t want monocultures for the big areas these are grown over,” explained Fleischer.

Better options: Woodland stonecrop, foamflower, wild ginger, Allegheny spurge, sedges, Liriope, Japanese forest grass, horny goat weed, Plumbago, Biokovo® or ‘Karmina’ geranium and weeding redbud.

• Loosestrife

“It’s beautiful. It’s my favorite invasive,” Fleischer joked. Loosestrife is popular because it’s pretty, has a long bloom period, grows well in wet and dry soils and has a great urban tolerance. But in addition to being invasive, breeders have made “bold claims of sterility” and the chemical treatment needed to tame it affects water quality.

Better options: Blue vervain, gayfeather, spiked speedwell, Culver’s root and Salvia.

• Miscanthus (Chinese silver grass/maidenhair grass)

In large field settings, this grass offers significant carbon sequestration, and its high yield makes it a favorite choice as a biofuel. In a landscape setting, it also boasts vigorous growth and is good for screening. But it is an ecological concern, being invasive, overused and useless as a food source for pollinators. “It’s just messy,” Guthrie admitted.

Better options: Switchgrass, little bluestem, big bluestem, blue grama grass, prairie dropseed and yellow prairie grass.

So what’s next on the list of mainstays that may need swapping? Guthrie and Fleischer said possibly Rose of Sharon, Nandina (heavenly bamboo), Mahonia and Heptacodium – all are native to east Asia, not North America.

by Courtney Llewellyn