by Andrea Laine, EMGV
After several years of trying to stay ahead of the weeds in my landscaped beds, I am coming around to an option I had not seriously considered before: planting ground covers as weed control.
A variety of annual and perennial broadleaf weeds consider my yard home year round. Most of them I deal with by manually pulling. Dr. Joe Neal, professor of weed science at NCSU, recommends a frequency of every two to three weeks. Call me crazy, but I have never minded hand weeding. It feels meditative while I am doing it and afterwards, too, when I look upon my tidy garden.
Unfortunately, hand-pulling does not work for creeping woodsorrel (Oxalis corniculata L.). Even after a good rain and using a weed digger, it is difficult to get the root up on a younger plant. I find it easier to let it grow a bit which gives me more plant above ground to grasp and pull. But allowing any weed time to mature is dicey: weeds multiply so quickly and aside from being unsightly, rob your favored plants of moisture and nutrients in the soil. Encroachment is inevitable with woodsorrel as it spreads by rhizome, stolon and/or rapidly germinating seeds.
I used to view ground covers as boring plantings; something you chose for a spot where it was difficult to grow anything else, or something non-gardeners or commercial properties planted to paint a spot green and call it landscaped. (Pachysandra comes immediately to mind.) But looking out my kitchen window last November at the way a few biennial columbine plants (Aquilegia canadensis) have reseeded so profusely over just a few years and now expertly cover a large part of the ground in one bed (i.e. no woodsorrell there), I am beginning to understand the concept and consider the possibilities.
Ground covers are plants that grow relatively close to the ground and spread freely to create a mass planting. The denser they are, the better they will be at shading the ground, thereby robbing weed seeds or rhizomes in the soil of the light needed to grow. If desired for weed control, seek out evergreen ground covers.
Columbine isn’t traditionally considered a ground cover but it does the job nicely. Some common ground covers are already established in my landscape; pictured below left to right they are: golden creeping jenny (Lysimachia nummularia ‘Aurea’ ), creeping juniper (Juniperus horizontalis ), oregano (Origanum heracleoticum ‘Greek’ ) and Mrs. Robb’s bonnet (Euphorbia amyglaloides, ‘robbiae’).
A blank canvas
My thoughts of “too much columbine” have turned to “need more variety of ground covers.” Ground covers will be the new blank canvas. I am not choosing ground covers instead of more ornamental perennials and shrubs. I am choosing ground covers over open soil or a blanket of mulch which can be expensive and labor intensive when used for large spaces. Rather than fretting over too much columbine, I will consider it a placeholder and an organic mulch. When I am ready to plant something among it, I will simply edit out some columbine and insert a showier ornamental.
Where you have stubborn weeds, consider planting a more attractive ground cover. More plant suggestions appear in the links below.
Sources & Further Reading
Identifying specific weeds: https://projects.ncsu.edu/cals/plantbiology/ncsc/containerWeeds/list.htm
Creeping woodsorrel: https://plants.ces.ncsu.edu/plants/all/oxalis-corniculata-l/
This link lists dozens of groundcover suggestions for Georgia landscapes. Almost all will also survive in Durham County (Hardiness Zone 7). https://secure.caes.uga.edu/extension/publications/files/pdf/C%20928_2.PDF
At heights of three to 12 inches, miniature roses can be groundcover: https://content.ces.ncsu.edu/roses-for-north-carolina
Low-growing junipers make excellent groundcovers: https://content.ces.ncsu.edu/junipers-in-the-landscape
More groundcover plant ideas: https://www.missouribotanicalgarden.org/Portals/0/Gardening/Gardening%20Help/Factsheets/Ground%20Cover%20Plants66.pdf