The exotic (non-native) Japanese Pachysandra (Pachysandra terminalis), Lesser Periwinkle (Vinca minor), English Ivy (Hedera helix) and Wintercreeper (Euonymus fortunei) have long been staples of New England gardens for their shade tolerance and ground covering habit. Go to any garden club sale or plant swap in the spring and you’ll find these plants available by the bucketload — but if you live in the northeast US and have a bit of woods separating your property from your neighbors, think twice before bringing any of these plants home.
Because these plants spread aggressively by their roots or stems, when they are planted adjacent to moist woods in New England, they can quickly spread into the woodlands, choking out anything else that happens to be growing there and threatening unique and fragile woodland plant communities. English ivy and Wintercreeper also climb trees and can eventually kill them (not to mention the damage the ivy can do to your house if you allow it to climb walls).
And once these plants are established in an area to their liking, good luck getting rid of them if you ever decide you’d like to plant anything else! Pictured below is a small woodland buffer in Sudbury, MA, highly valued by the homeowner for its summertime privacy screening from neighbors. The vinca, pachysandra and English ivy planted decades ago near the house have escaped into the woods and the homeowner is frustrated that the young trees are dying, and that she cannot get seem to get any other plants established here:
If you drive around the leafy outskirts of Boston MA, you might be impressed at the established trees, especially in older neighborhoods (more than 50 years old). Many of the spaces between houses are heavily wooded — in New England, trees don’t need much encouragement to grow. But take a closer look at what else is growing under those trees. You’ll quickly notice those same few species of plants in just about every neighborhood.
You won’t see these plants on New England state invasive plants prohibition lists, simply because they don’t reseed themselves the way invasives such as Asiatic bittersweet do — by birds eating and dispersing their berries far and wide. They spread mostly from being planted in favorable conditions near moist woodlands. As so much of our region is now gobbled up by roads and development, those wooded buffers between homes are often the only wildlife habitat that remains in metropolitan areas of the northeast. Although birds might utilize the trees for their nesting opportunities and insect forage, a buffer taken over by invasives will lack most of the ecological benefits provided by a diverse understory of native woodland plants. For homeowners that understand that their yard plantings have an impact on the wider environment, a little effort to search out appropriate native plants will go a long way towards increasing the biodiversity and wildlife value of suburban yards. Not to mention, the results are much more interesting!
So, if you do border on moist woodlands, what are some “safe” alternative groundcover native plants to look for? Try the beautiful running foamflower (Tiarella cordifolia), which is (mostly) evergreen and forms a thick weed-suppressing mat under trees:
There is also a native pachysandra called Allegheny Spurge (Pachysandra procumbens) that hails from the southeast US, but grows happily in my zone 5 central Massachusetts garden. It looks a lot like Japanese pachysandra but its leaves are not as glossy:
American Yew (Taxus canadensis) is a native yew that loves the cool, damp shade of New England forests. Unlike its popular Eurasian cousins that are standard as sheared foundation shrubs in the US (T.cuspidata, T. baccata, T. x media), this yew stays low (2-3′) and spreads up to 10′ from its base:
Because it’s a deer favorite, wild populations of American Yew are becoming rarer in Massachusetts, as suburbia pushes outwards and deer populations soar out of control. Unlike other conifers, however, American Yew will resprout after being pruned (by deer or hedge-clipper), so if you live where deer populations are somewhat under control (or you are willing to put up deer fencing), the evergreen Canada yew is worth growing to help preserve local populations and genotypes.
Wild ginger (Asarum canadense) is another native that will fill an area in moist shade. It’s growing here at Garden in the Woods along with several types of fern and Allegheny Skullcap (Scutellaria serrata).
More native eastern ground covers suitable for moist shade include mayapple (Podophyllum peltatum) which typically grows in thick patches under oak trees:
I don’t believe Japanese pachysandra or Vinca will disappear from our home landscapes any time soon, and admittedly, as long as they are contained, they should not cause much harm. A patch CAN be useful if you have dogs. Our border collie Speck hates the heat of summer and loves to cool off in pachysandra, which appears to bring him much relief. I have left one well-contained patch as his personal dog bed…
Read about my efforts to eradicate a large patch of pachysandra that spread into a nearby moist woodland area on my property in The Year I Shall Win the Pachysandra War how many tablets of viagra should i take. Several years later, I can attest that I have finally won this war (I only pulled a few persistent bits of root this year), and I now see native plants making a comeback.