One of the lovely sights in the late summer / early fall, when much of the garden is winding down, fading, losing its spring and early-summer luster, is the emergence of the late-flowering perennials. And among these Solidago canadensis is one of the most vibrant. Plumes of bright golden yellow flowers top the upright, slender stems that can reach a height of as much as six feet or more. Some of the stems will topple, and either need to be staked or removed; if you want to do neither, or if you'd like your plants to be a little shorter and fuller, you can pinch back the growing tips in the late spring.
Our native goldenrod is ideal for the back of the border, both for the fact that they tower over all other flowers but the tallest dahlias, and because the bottom twelve inches or so at the base are often bare, and so benefit from having that fact hidden behind some lower growing plants. (And medium-height plants growing in front of the goldenrod can help prop up any leaning stems).
Solidago canadensis - Goldenrod
Of the more than seventy species of Solidago native to North America, only a small handful of them make their home in the Pacific Northwest; most of them are the taller, upright variety, though there is one alpine variety, S. spathulata, that is both small and for dry conditions, an excellent candidate for a container or rock garden. The upright varieties are more flexible in terms of sun and water: Full sun to partial shade will suit them equally, and though they prefer average amounts of water, will tolerate drier conditions (which will also keep their spread by underground rhizomes a bit in check; they also can spread by seed, so don't be surprised to see them occasionally appear a ways from their original location, usually where they find a more well-watered site). Of all of these, S. canadensis is by far the most commonly available species.
And let me put this debate to rest: Goldenrod does not cause allergic reaction or hayfever; it has long been confused with another plant that is similar in appearance, tansy ragwort (Ambrosia sp.).
Relatively maintenance free and untroubled by most pests and diseases, it is also highly favored by butterflies and many other beneficial insects. The seeds after flowering are a good autumn food source for song birds. It is a useful plant to have in your garden, as well as a sunny, refreshing burst of late-season color.
Common Name: Goldenrod
Origin: North America
Characteristics: Narrow, long, toothed leaves arrange themselves along upright stems that can reach as tall as six feet, topped by bright golden yellow flowers that are a multitude of small heads grouped together into slightly arching plumes.
Culture: Solidago will thrive in full sun to partial shade, ample water and good drainage, though slightly drier conditions will somewhat curb their tendency to spread.
Pests/Diseases: Mostly pest and disease free; when overcrowded however, plants can sometimes develop rust fungus. Also, if drainage is poor, root rot can occur.