Sustainable enough

I just listened to an informative interview with Uli Lorimer, director of horticulture at Native Plant Trust, our local native plant society in Framingham, Massachusetts. Uli was a guest on garden writer Thomas Christopher’s weekly radio show and podcast, Growing Greener. Thomas focused the interview on native and locally adapted plants.

Monarch on New England aster

    Together, the two men proposed a type of garden that’s designed to serve the interests of as many living things as possible, not just humans. Instead of choosing plants because they’re pretty, you’d select what performs the most useful functions for your garden ecosystem. You’d put aside neatness as a top aesthetic priority.

Goldenrod is a key player in this meadow ecosystem in Maine

    This is the path I want to follow, but I argue that we don’t all have to arrive right away. Uli pointed out that much important information about native plants hasn’t yet been ascertained, and the rest hasn’t spread past native plant enthusiasts. As a start, he suggested, growers should be using plant labels to tell where plants came from and how they were propagated.

A plant label that lists the seed source and nursery location

    Native Plant Trust advocates growing plants that evolved in the local ecoregion, the area with the same environmental conditions they'll find in your garden. In addition, they value genetic diversity within each species, meaning plants that are grown from seed, not cloned through cuttings or divisions to be genetically identical. 

    A genetically diverse, locally adapted plant population will be well-equipped to deal with shifts in its environment, including rapidly changing climate. But so far, conventional growers haven’t figured out how growing from seed could be scaled up to their volume of production in a financially viable way. In addition, we consumers have been trained to want reliably uniform plants, which is what you get with clones. Seed-grown plants are variable. 

Mass produced plants are genetically identical and uniform

    Native Plant Trust sells about 300 species of locally adapted native plants at their garden shop. They’re grown from ethically collected wild seed of known New England provenance. But what if the shop doesn’t offer a native plant you’d like to buy? Is it wrong to buy plants that don’t meet their high standards?

    This brings me to my point. I think becoming a sustainable gardener, and a native plant gardener, can be a process. You don’t have to change everything all at once. After 35 years, my garden is full of nonnative plants I’ve chosen over the years. Many of the ones that have survived are plants I love and wouldn’t dream of removing. We have a history together.

They'll have to pry my nonnative white bleeding heart from my cold dead trowel

    Every year as I learn more about native plants, I add more of them to the garden. I adjust my gardening approach to accommodate their needs and welcome a richer population of wildlife, especially insects. Is it still OK to buy nonnative plants because you like them, or North American native plants even if they’re not local, they’re “improved” cultivars of native species, or they’ve been propagated asexually? I think it is. If we’re thinking about these issues, we’re moving toward full sustainability, even if we’re not there yet.

Newly planted mountain mint from NPT--native, locally grown and adapted

 

Making themselves at home

This August I’m keeping an eye on native plants I’ve recently added to the garden. I have to admit that not every native I’ve brought home has settled in easily. But an inventory of the newish plantings under the shade of our dawn redwood (Metasequoia glyptostroboides) shows that some are chugging along.

Before recent additions: shade-tolerant plants under the dawn redwood

    I have high hopes for New York ironweed (Vernonia noveboracensis). This will grow to a shrub-sized perennial, up to 6 feet high and 4 feet wide, with purple flowers in late summer and fall. 

New York ironweed blooming last fall

Doug Tallamy’s Bringing Nature Home web site notes that ironweed is a caterpillar host plant for 18 species of moths and butterflies in my area. So far it’s only about a foot tall, but it has pleasing feathery foliage. When the sheet composting area decomposes enough for planting, I might move the ironweed forward away from the tree, since it grows in sun in the wild.

    I love the dark reddish-brown flowers of Carolina allspice (Calycanthus floridus), a beetle-pollinated magnolia relative also known by the common name of sweetshrub for its flowers’ fruity scent. 

Carolina allspice flowering in Central Park

I first planted this shrub in significant shade next to a Japanese stewartia (Stewartia pseudocamellia). It has survived and flowered, but it’s not making many branches. When we took down the hemlocks near the dawn redwood, a sunnier patch opened up. I took the opportunity to try Carolina allspice again.

    Another native shrub that seems to be thriving is coastal doghobble (Leucothoe axillaris). Its best feature is its low, arching sprays of shiny leaves. Native plant expert William Cullina explains that the common name describes the tangled thickets leucothoe creates in the wild that even a dog can’t wriggle through.

Shiny foliage of coastal doghobble

     Leucothoe is often recommended with other broadleaf evergreens for foundation plantings. I inherited lots of those: rhododendrons (Rhododendron spp.), mountain laurels (Kalmia latifolia), and Japanese pieris (Pieris japonica), but I’d never grown leucothoe until I realized it was a native that might do well under the shade of the dawn redwood, and so it has. Those leaves are still shiny and pristine in August, which is more than I can say for most of the foliage in the yard. I haven’t seen any flowers yet. They’re going to be little dangling white bells.

    By the way, neither Carolina allspice nor the leucothoe is actually native in the Northeast. They’re both from the Southeast, but since they can grow here, I’ve decided to give them a try. We each get to decide how native our natives are going to be. If I were a true purist, I’d restrict myself to plants from my ecoregion, the Boston Basin. So far I’m not willing to be that exact.

The Boston Basin is my ecoregion

    A true New England native is already established next to the dawn redwood: winterberry (Ilex verticillata). This has grown into a small double-stemmed tree and produces masses of red berries that birds eat during the fall and winter. I’m glad to know that it also provides caterpillar forage for 42 moth and butterfly species.

Winterberry fruit in late fall