By Cathy Krar, Master Gardener, SCMG
Don’t do as I do … do as I say! I am guilty of letting an invasive species
run amok in some of my gardens. And not that I haven’t tried to scale
back this charming little groundcover with the violet pinwheel flowers.
BUT it is very fast growing, extremely adaptable, and it is a tree killer!
Periwinkle or vinca minor is a perennial evergreen that is NOT native and
arrived on North American shores in the 1700s from Eurasia. It was
initially regarded as a low maintenance ornamental. Now, it has become
highly problematic in southwestern British Columbia, and areas
extending from Ontario to Nova Scotia. It doesn’t stay put and too often
escapes captivity and aggressively spreads into our forests and along
waterways.
The appeal is that it is very easy to grow in dry or shady conditions, with
attractive glossy oval leaves. It belongs to the Dogbane family and
creates dense mats of growth that choke out other plants. Its thick
ground cover prevents tree seedlings from becoming established.
You can argue that periwinkle’s density makes it an ideal candidate for
controlling soil erosion, and you would be correct. You can say it is
popular due to its spread-ability over larger areas, and again you would
be right. However, periwinkle can reproduce by seed, root fragments
and rhizomes, making it a formidable opponent to eradicate.
When you consider the potential loss of habitat for insects, mammals,
bees and salamanders, and the impact on local ecology of native plants
and trees. It now becomes important to prevent its rapid spread
through our forest’s understories.
Management practices are important in prevention. Educating
gardener’s and horticulturalists isn’t enough. Home gardeners need to
be informed as well. I have resorted to solarizing and covering swaths of
periwinkle with tarps; and cutting back areas and laying cardboard boxes
with mulch on top to suppress growth.
Consider planting non-invasive native species like:
Bunchberry or creeping dogwood that makes an excellent ground cover
in moist woodland gardens.
Woodland strawberry spreads by runners and grows naturally in
prairies, rocky areas, and tough to thrive areas under spruce or pine.
False lily of the valley is a taller ground cover with pretty heart shaped
leaves. It thrives in moist shade with mature soils.
Wild geranium or cranesbill is a perennial herb that bloom well in part
shade to shade. It does enjoy rich, acid soil
Tiarella cordifolia or foamflower is an attractive ground cover for shady
wooded sites, and forms colonies.
Princess pine clubmoss aka Watchchain plant looks like a tiny 6-inch
pine tree. It is a succulent plant that does well in shaded areas that has
limited food traffic
Argentina anserina or silverweed is a creeping, trailing plant that can be
found on rough grassland, roadsides, sand dunes and waste ground. It
creates creeping mats of silvery, down leaves.
Low-fast Cotoneaster is a low growing woody evergreen shrub with
small pretty leaves and small white flowers. It likes full sun to partial
shade with moist well-drain soils.
Much to my amazement nurseries in our area still supply this pretty little
menace. Perhaps we need to lay a little guilt trip on those horticultural
centres that are still selling and promoting common periwinkle. Please
don’t trade or purchase this plant.
