Native plants contained by sidewalk at Penn State Extension's Dauphin County office. Photo credit: Lois Miklas
Have you ever planted a beautiful specimen plant, nurtured it, admired it, and then regretted your actions? Many gardeners have. Even if you still have a plant or two growing and taking up more real estate than you have allocated for them, there are some things you can do to contain, or restrict their growing habits.
Naturally, plants will do what they were intended to do. Given the right conditions, plants will grow and multiply. Plants spread in a number of ways. One of the most obvious ways some plants spread is by self-sowing. It is easy to identify the self-sowers. After blooming, these plants produce seed pods which contain many, many seeds. Examples of self-sowing plants that spread rapidly are black-eyed Susan (Rudbeckia hirta), yarrow (Achillea millefolium), and columbine (Aquilegia canadensis). The best way to contain self-sowing plants is to deadhead, removing the flowers after they have reached their prime but before they dry out and go to seed. Be attentive throughout the growing season, as flowers will fade at differing rates.
Another group of plants claim their territory by sending out rhizomes (swollen underground stems) or stolons (above-ground runners). These plants root and form new plants at the nodes where the stolons and rhizomes come into contact with the soil. Iris, lily of the valley (Convallaria majalis) and bee balm (Monarda didyma) are examples of plants that spread by rhizomes. Some common creepers that spread by stolons include creeping buttercup (Ranunculus repens), bugleweed (Ajuga reptans), and lamb’s ears (Stachys byzantina).
These spreaders can be controlled and contained if you limit their access to soil by planting them near barriers such as sidewalks, walls, and road edges and cutting them back when they have reached the outside edge of their boundaries. You may even want to consider planting these fast spreaders in containers.
You can make a simple and inexpensive plant barrier by cutting the bottom and top off of a plastic kitty litter container, forming a round of plastic about eight to ten inches wide. Place this in the ground around the suspect plant, leaving about two inches of plastic above the soil level. You can use bark mulch to conceal the above-ground plastic.
Before you select a new plant for your garden, do some research. Think, “right plant, right place.” Use the information from plant tags and container labels. Follow up with a review of plant catalogs and gardening books to learn about a plant’s growth habits before placing it in the ground. If you just have to have that floriferous wonder and you don’t know much about it, consider assigning the plant to an appropriate pot so you can observe its growth habits throughout a growing season and before you assign it to a regrettable garden location.