In our fourth year of growing this plant in zone 3, I think of it as a wonderful groundcover, although I can see why some gardeners might view it as a nuisance. The tiny clump we first planted has now spread to cover a large area, and although it's taken over a couple of sweet peas planted from seed and a delicate alpine plant that was failing anyway, we have high hopes that it will beat out the lilac suckers that come through our fence from our neighbours' yard. In short, it is a thick groundcover, about 15 cm tall, that easily crowds out weeds. However, the roots and spreading stems are quite shallow, so transplanting and controlling the spread of this plant are both fairly simple. Although it isn't too picky, it seems to prefer some sun to full shade in cold climates, and appreciates some amendments to the soil before planting.
Although this plant grows very well for me in my backyard garden, I have killed some by transplanting it in front of our house. I also gave some to a relative in Calgary (also zone 3), in whose shady bed it never really took off. However, a stem that appeared to have no roots that my three-year old "planted" in our newly dug and amended front garden this year is actually growing and flowering. I believe that this plant will grow well in our area, as long as it gets a little sun, a little TLC before planting, and good snow cover over the winter.
Sweet woodruff: tough enough to plant around the sandbox
Besides crowding out the dandelions and chickweed, what else is this plant good for? Even during our cold winters, it often emerges from the under the snow with some green growth, giving it a good head start when your garden needs it most. The tiny white flowers appear in clusters above the leaves in the spring, giving it the alternate common name "wild baby's breath". In a large clump or mass, the display is very pretty, and the plants sometimes rebloom in summer. The tiny flowers are also sweetly scented, and stems will last about a week in a glass of water. An established clump can also supply plenty of flowers to pick even for very enthusiastic children, without showing the bare patches. And the foliage itself also smells wonderful and may repel moths when it is dried, making it a good ingredient in homemade potpourri.