by Missy Fabel
I confess: Throughout the early aughts, I had a love affair with mulch. Each spring, I would throw two large trash cans into the back of my Honda minivan (a necessary, unsexy vehicle for three small children in car seats), head down to the local recycling center, kids and pitchfork in tow and just dig in. I loved the smell. I loved the steam which would escape into the cool spring morning each time I pitched. I loved the weight of those trash cans, which I would refill again and again, sometimes returning to the recycling center two or three times in a single day. I loved the warmth on my hands and knees as I gently spread mulch around my beds. I loved that feeling of neatness and the satisfaction of seeing my hard work all laid out: the deep dark smelly brown sea making the crowns of my emerging perennials pop green in comparison. The promise of spring.
Yet, as sometimes happens with affairs of the heart, this one was doomed. The breakup happened slowly over time. I was and am ecologically minded, so I knew that leaf litter in my garden was a good thing and should be left. The solution? A light dressing of mulch over the fallen leaves in early spring. Next, I started experimenting with Phlox stolonifera (creeping phlox) and Tiarella cordifolia ‘running tapestry’ (foamflower) and discovered it is impossible to mulch around them without smothering them. Then, the following spring, I noticed seedlings of Aquilegia canadensis (Eastern red columbine) volunteering in and around those impossible to mulch spaces. Each spring, my visits to the recycling center became less frequent. My favorite trash cans started to crack. We got rid of the minivan.
The last straw? I simply ran out of space in my garden.
Native groundcovers have now taken over my affections. Not just one native groundcover will do. No, when it comes to groundcovers, I am polyamorous. I must have a mix – a matrix of different species of grasses, sedges, perennials, biennials, and annuals. Each one brings a certain, intimate Je ne sais quoi to my garden, filling gaps by virtue of its growth habit and reproductive strategy. Knowing what each one brings to the landscape, not only aesthetically, but functionally is key to sustaining a long, happy affair.
Layer the Right Players
Let’s face it. Plants are selfish, caring only about one thing: making more plants, whether through sexual production of seeds or vegetative reproduction through rhizomes and stolons. Some species employ multiple strategies in their quest for reproductive success. When considering a groundcover matrix, consider how each plant will function in the landscape.
Will it spread over the ground, sending out long stolons to weave in and out of other perennials? Or spread under the ground by rhizomes, underground stems from which new plants arise and can form dense stands? Or spread by seed, filling in gaps helter-skelter, whether as an annual biennial or short-lived perennial? Will it be able to grow in the shade of larger perennials later in the season? Or will it complete its life cycle before the trees leaf out, a true spring ephemeral leaving a gap in the bed? Is it a highly competitive species, adaptable to a variety of site conditions, crowding out other species? Or is it a species that will drop out if certain site conditions are not met?
There is not an exact formula for pairing companions; however, to cover an area relatively quickly, I like to choose one to three species of rhizomatous and stoloniferous plants, such as Carex appalachica (Appalachian sedge) or Fragaria virginiana (white woodland strawberry), to make up 60% to 70% of the matrix. For the remaining plants, I prefer biennials and perennials that are prolific self-sowers; I count on them to drop in and out of the planting and to provide dynamic seasonal interest. Mertensia virginica (Virginia bluebells), Aquilegia canadensis (eastern red columbine) or Lobelia spp. (both cardinal flower and blue lobelia) are good choices for reseeding.
There Are No Rules
As plantsman Roy Diblik of Northwind Perennials is fond of saying, “There are no rules.” Yet, when creating a groundcover matrix, remember that you are also building a plant community, one that will change throughout the growing season from year after year as plants adapt and mature. Look to the natural world for inspiration and don’t be afraid to try unusual combinations. This past spring, I discovered a carpet of Polystichum acrostichoides (Christmas fern) a shade loving woodland fern growing in full sun in the power lines right of way in a local preserve. The catch? It was growing underneath taller, invasive shrubs, but also playing nicely among the native Schizachyrium scoparium (little bluestem) and Apocynum cannabinum (dogbane) on the edges.
For shady woodland areas, the classic combination of Carex pensylvanica (oak sedge) or Carex appalachica (Appalachian sedge), Tiarella cordifolia ‘Running tapestry’ (foamflower), and Phlox divaricata (woodland phlox) cannot be beat. Add in pockets of deer resistant Mertensia virginica (Virginia bluebells) and/or Stylophorum diphyllum (wood poppy) for an earlier show in spring. Drifts of evergreen ferns such as Polystichum acrostichoides (Christmas fern) and late season Eurybia divaricata (white wood aster) provide fall and winter interest.
In sunnier spots, my darlings are Sporobolus heterolepis (prairie dropseed), Allium cernuum (nodding onion), Asclepias tuberosa (butterfly weed) and Fragaria virginiana (white wood strawberry). While the prairie dropseed may be slow growing, both the nodding onion and butterfly weed will self-sow the second season to fill in the gaps. In the meantime, the quick growing (and often evergreen) strawberry will send out runners, weaving in among the new plantings, while its open form still allows for seedlings in the spring and other perennials later in the season.
I can no longer remember who once told me that pachysandra was the vinyl siding of the suburban landscape, but the phrase stuck. For clients looking for that evergreen aesthetic in foundation plantings or under shrubs, then Packera aurea or Packera obovata (golden groundsel) is the way to go. The glossy leaves remain evergreen and in early spring are adorned with bright yellow flowers. It is a versatile and quick spreading groundcover growing in sun or light shade, preferring mesic to moist soils. I have even experimented with planting it under Scoparium schizachyrium (little bluestem). The deep roots of the little bluestem do not compete with the shallower roots of the golden groundsel and the groundsel provides an early spring show of color before fading into the background once the warm season little bluestem begins active growth.
Be Plant Polyamorous!
Remember, a groundcover is just one component of a layered landscape and need not be a monoculture. A matrix of species is not only bio-diverse, but more resilient and creates dynamism in the landscape. It’s also really fun to be in love with multiple native species!
Author’s Note: If you’re looking for plant ideas, refer to my Effortless and Evergreen Plant List.
About the Author
Missy Fabel is a landscape designer, consultant and naturalist in Chappaqua, NY. She is a Steering Committee member of the Native Plant Center at Westchester Community College and the Director of Horticulture at Plan it Wild. She can be reached at info@MissyFabel.com.
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