Recently, our English partner in GardenRanting – Anne Wareham – commented (on this post), “It would be useful for someone from the UK to know more about why native plants in America are fundamentally different from others, so that they impact on design this way.”
Good question! And I promised to answer, starting with the disclaimer that I can only speak for my region (since in the U.S. there are so many different ones).
Native Large, Deciduous Trees – We’ve Got ’em!
Here in the Maryland, like much of the East, land was mostly covered in deciduous forest, so there are plenty of excellent deciduous trees to choose from that are native here. And according to Doug Tallamy, trees like White Oaks are the most important native plants for the wildlife we want to preserve and protect.
Conifers? Not So Much
Here in the East, native conifers are few and far between – at least ones that would fit in most gardens. Sources agree:
- Margaret Roach’s favorite conifers include just one native to her New York garden – a dwarf White Pine.
- The Birds and Blooms list of dwarf conifers for small spaces includes a creeping Juniper that’s native, plus Arborvitae and Bald Cypress.
- Fine Gardening recommends the Eastern White Pine, Colorado Spruce and Western Arborvitae – all U.S. natives but not here in the East. One more list from Fine Gardening includes no natives to eastern half of U.S.
Now for shrubs – the plants that form the bones of our home gardens, that make them look like gardens even in winter, these are the nonnative plants we need the most, in my experience and observation.
Of all the shrubs and small trees I’ve grown in my two Maryland gardens, the only natives are Ninebark, Fothergilla, Redbud, Dogwood, and some of the near-native Oakleaf Hydrangeas. None are evergreen.
Now for the nonnatives. Pictured above are some that have been major contributors to my gardens: Caryopteris, Weigelia, Acuba, Crepe Myrtle, Spirea, Pieris japonica, Lacecap Hydrangeas, Beautyberry, Forsythia, Roses and Nandina. Others not pictured include Korean Boxwood, Azaleas, False Holly, Purple Smokebush, Koreanspice and Doublefile Viburnum, Japanese Maple, Arborvitae, Chinese Juniper, Acuba, Abelia, and Mock Orange.
And these are the nonnative evergreen shrubs I’ve used as foundation plants – the ‘Otto Luyken’ laurels above in my former garden (plus Korean Boxwoods), and below, Azalea, Spirea, ‘Goshiki’ Osmanthus, and Nandina along the front of my current home.
The Need for More Landscape-Worthy Shrubs
A writer for Ecolandscaping.org addresses this problem in his article High Impact Native American Shrubs”. (Spoiler alert – there’s not much except Ninebark.) Bolding by me.
One of the components of my research and extension program at the University of Connecticut has been the evaluation of native shrubs for landscape suitability.
One of the issues associated with native plants has been their blind recommendation without knowing their landscape adaptability and the false notion that all native plants are well suited for landscape purposes. For example, highbush blueberry (Vaccinium corymbosum) is commonly recommended as a substitute for invasive winged euonymus (Euonymus alatus) because both have vibrant red fall foliage. However, blueberry is not well adapted to the locations where winged euonymus is used, and it performs poorly or dies. Failed attempts at using native plants result in future reluctance of homeowners, landscapers and growers to embrace native species as viable alternatives to invasive species.
The green industry would benefit from a broadened palette of versatile and adaptable native plants to meet the growing desire to utilize natives in landscaping.
Speaking of blind recommendations of native plants, one often-recommended source of information for home gardens is this booklet of native plants from the U.S. Fish & Wildlife Service. Its meagre photos and descriptions give no indication as to which plants perform well in actual gardens, but this inappropriate resource continues to be cited because nothing appropriate exists. So far, anyway.
The Problem of Groundcovers
Groundcovers are another essential plant group in successful landscapes, the most common one being turfgrass. I quit lawns about 12 years ago and have tried dozens of alternative groundcovers since. With precipitation, which we have here, ground must be covered or weeds will do it for us. And I’d rather cover ground with plants than with mulch.
The only successful native groundcover I’ve found and recommend is Packera aurea, a woodland plant that prefers shade or part sun. The nonnative ones that perform well in my garden are ‘Ice Dance’ Carex. Sedum takesimense, Mondo Grass, Comfrey (Symphytum grandiflorum), Creeping Jenny, Liriope and Periwinkle. I hasten to add that none are growing where they might harm natural areas.
Annuals and Bulbs
Naturally, because this region has freezing temps in winter, none of the annuals that I grow – Zinnias, Sweet Potato Vine, Coleus, Iresine, and Morning Glory, and Bronze Fennel – are native, so they’d be missing from an all-native garden. My spring-blooming bulbs would be missing too – Daffodils, Grape Hyacinths and Spanish Bluebells.
Sun-Loving Native Perennials – Some Great Choices
Now for some good news! For a part of the country that was once forest and will revert to forest if given the chance, it’s surprising that there are so many sun-loving native perennials to choose from. In perusing my photo folder named “Favorite Perennials,” I came across some great native plants that have performed well in my gardens.
Above are Joe Pye Weed, Spiderwort, Aster, Amsonia hubrichtii, Goldenrod, Rudbeckia and Purple Coneflower. (The Coneflower may or may not be native to this region; some experts say it was introduced in the East by Lewis and Clark.)
I also currently grow these sun-loving native perennials: Crossvine, Honeysuckle (Lornicera sempervirens), Butterfly Weed (my new favorite perennial), Woodland Aster, Coreopsis, and Little Bluestem.
Sadly, perennials alone don’t make for a great-looking home garden. So when people ask me about pollinator gardens, for example, I say they’re a great addition to home landscapes but by themselves, no substitute for one that looks good all year round.
Favorite Nonnative Perennials
I’ve also grown many well-adapted nonnative perennials, including Daylilies, ‘Autumn Joy’ Sedum, Siberian Iris, Lamb’s Ear, Rose Campion, Russian Sage, Mexican Evening Primrose, Hosta, Pulmonaria, Catmint and Autumn Fern.
I hope this post demonstrates the contribution that nonnative plants make toward biodiversity in our gardens. I’m no ecologist (obviously) but wouldn’t these gardens be less biodiverse without the dozens of great plants from other places?
Back to you, Anne
I hope that answers your excellent question.