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

 

New perennials the easy way

To share purple coneflowers (Echinacea purpurea) with students in last month’s sustainable gardening course, I asked them to snip off the spiky brown heads of the coneflowers in the flower bed. Just drop those dried-up brown items on the ground, I confidently told them, and they’ll plant themselves.

    The reason I believed this would work was that the same method had succeeded for me. I’d purchased and planted a single potted coneflower. When I wanted to make more, I initially thought I’d have to divide the plant, cutting out a section of its stems and roots. Or I’d have to collect seeds, plant them indoors, and grow them to transplanting size under lights. 

Goldfinch feeding on coneflower seeds

    But there were so many of the “cones,” that I decided to try dropping some where I wanted new plants and see if something would grow. This worked surprisingly well, and now I have a line of coneflowers where I scattered those seeds. 

A patch of coneflowers has grown where I dropped seedheads in fall

The round seedheads are what’s left after the flowers are pollinated, seeds develop from each of the mini-flowers in the central globe, and the petals drop off. If pollinators are around to do their work, each cone can carry hundreds of seeds.

Each spike is a coneflower seed

    Some native flowers grow easily from scattered seeds. Black-eyed Susans (Rudbeckia hirta) do this every year in my insectary bed. This plant is a biennial with a lifespan of two years. It performs like a perennial, though, because the seeds that drop from the flowers grow into next year’s flowering plants. If you didn’t know, you’d think the parent plants lived on indefinitely. I write about these plants a lot because they’re among my most successful and lowest maintenance natives.

    Last year I attended a lecture on how to grow native perennials from seed. This is a way to create a genetically diverse plant collection, because seeds combine the genes of both parents. I learned that the process is much more complicated than what I’m used to with annuals and vegetables. Some perennial seeds need a period of sustained cold, which in nature would be provided by winter. Some need alternating warm and cold treatment. Some need help breaking through hard seed coats.

Trillium seeds require several cold and warm seasons before they'll germinate-photo Finetooth

    These perennials have evolved strategies to delay germination until the conditions are right. That’s how they maximize viable offspring and avoid being destroyed by animals or shouldered aside by other plants vying for the same sites and resources. But imitating the sequence of events that triggers germination in many native perennials would be tough, exacting work.

    The alternative is to let the process happen outdoors without intervening. Since I don’t need to produce large numbers of plants, I can let nature do the work. I’ve stopped reflexively dead-heading, removing flowers before they can set seed. I’m hoping that seeds of some of the new native perennials that flowered in my garden this year, including sweet goldenrod (Solidago odora), Stokes’ aster (Stokesia laevis), and blue-eyed grass (Sisyrinchium angustifolium) will surround their parents with the beginnings of small colonies next spring.

Blue-eyed grass flowering in June