Goldenrod Weeds

These Wildflowers Invasive, but Not the Cause of Allergies

Goldenrod (image) is not only breathtaking when in bloom but also not a health hazard.
David Beaulieu

Botany of Goldenrod

Plant taxonomy classifies goldenrod in the genus, Solidago. That genus name comes from two Latin words: solidus (whole) and ago (make). So in what sense can this plant make you whole? The name alludes to the medicinal uses (see below) for the weed. Many species exist. One of the more widespread (and more striking) types of this flower is common or "Canada" goldenrod plant (S. canadensis).

Goldenrod is an herbaceous perennial.

Traits, Plant Care

In addition to being the name of a wildflower, "goldenrod" is also the name of a color, defined as "a strong to vivid yellow." You need search no further for the defining characteristic of this plant, whose flower stalks bristle with numerous, small flowers of a vivid yellow or gold. The flowers of S. canadensis occur in tufts, and the overall plant can grow as high as 10 feet tall (but it is more common for it to stay about half that height). Although there are many types of goldenrod flowers, this perennial is, generally speaking, a tall, slim plant (4 to 5 feet on average) topped off with fluffy, golden flower spikes. Thus the most likely origin of the common name: golden (for the flower color) + rod (a reference to the spindly shape of this wildflower).

Most types are native to North America, where they grow as wildflowers in pastures and along roadsides.

There are goldenrods as far north as USDA zone 2 and as far south as at least zone 8.

In its native region, it requires little care. For the sake of having a tidy yard, you may wish to cut down the dead stalks in late fall and compost them. Divide and transplant in spring if you wish to increase your supply of the plant (but see below about the plant's aggressiveness).

These weeds often develop rounded swellings on their stems called "galls." The galls are caused by insects but do not do any harm.

What Are Some Warnings About Growing Goldenrod? 

A warning about growing this weed is that it is an aggressive spreader that may take over an area and form a monoculture (that is, no other plants will be able to compete with it). This wildflower may thus be considered an invasive plant outside its native range. The plants spread not only by reseeding, but also via underground rhizomes, which is a potent combination that helps account for their being invasive.

Does It Cause Allergies? How Is It Different From Ragweed?

Fortunately, one warning that you will hear concerning this flower is mainly a myth. People who speak of "goldenrod allergy" are usually guilty of blaming the wrong weed for their hay fever, the real culprit being ragweed (Ambrosia spp.). Once you see what ragweed looks like, there is really no mistaking the two plants, because they look totally different from one another. Ragweed is one of the truly noxious weeds.

Growing Goldenrod

Many gardeners (especially lovers of native plants in North America) are interested in growing this plant, since it has such lovely flowers.

Goldenrod, generally, will perform best in full to partial sun and in a well-drained soil, but these wild plants will also tolerate clay. Cultivars exist that do not spread as aggressively as do their wild cousins; one is 'Crown of Rays.'

If you grow a wild version, one way to check the spread of its rhizomes is by using bamboo barriers. Another way (if you have just a small number of the plants) is to transplant often, so that your goldenrod never quite feels "at home." Once it becomes settled, that is when it tends to start spreading.

To keep goldenrod flowers from reseeding, cut off the flower heads before seeds develop. Since goldenrod plants have stiff stems, it is easy to use them in flower arrangements.

Medicinal Uses 

Medicinal uses traditionally have ranged from anti-inflammatory to diuretic uses.

It was also used as a vulnerary herb (that is, a plant used to promote the healing of wounds), as were sweet woodruff (Galium odoratum) and yarrow (Achillea millefolium). 

Is It a "Wildflower" or a "Weed"?

Should this flower be considered a "type of wildflower" or "type of weed? Since the difference is a matter of opinion, the answer is really up to you. It is an attractive plant only when in bloom; its stalk and leaves have a "weedy" look. Bloom time, depending on the type of goldenrod, is from mid-summer or late summer until frost in cold climates. For some, the beauty provided by this flower for those two or three months is enough to earn it a spot in their wildflower garden.

Wildlife Attracted to Goldenrod

This flower is widely known as a plant that attracts butterflies. Canada goldenrod is a food source for the following butterflies:

  1. Monarch
  2. Clouded sulfur
  3. American small copper
  4. Gray hairstreak

Goldenrod attracts a number of other insects, too, including bees.

Other Types

Audubon's Field Guide to New England states that there are more than a dozen species of Solidago in that region. This, despite the fact that most people, when they hear "goldenrod," assume that there is only one type. True, S. canadensis is especially pretty and very common (thus the alternate name, "common goldenrod"). But S. speciosa is also a handsome plant. In fact, the latter is so striking that its common name is "showy goldenrod."  It grows to be 2 to 3 feet tall. Here are some other kinds of some note (all are native to New England and to surrounding regions):

  1. Zigzag (S. flexicaulis): The origin of its colorful common name lies in the fact that its stem actually does zigzag. It grows to be 3 feet tall.
  2. Old-field (S. nemoralis): Somewhat on the short side, by comparison, old-field goldenrod stands 2.5 feet tall. Its flower heads are more cylinder-like than tuft-like.
  3. Bog or "swamp" goldenrod (S. uliginosa): As its common names suggest, this 4-foot plant will perform better in areas with wet soil than most types.
  1. Seaside (S. sempervirens): Just as there is a goldenrod for swampy areas, so there is one for the seashore. This is the kind that you will want to grow if you need a salt-tolerant plant. Its height varies greatly depending on growing conditions (1 to 8 feet tall).
  2. White goldenrod (S. bicolor): Noteworthy simply because it does not have golden-yellow flowers, this white-flowered kind grows to be 1 to 3 feet tall.

Aster Family

Goldenrod plants are in the aster family. A huge family of flowering plants, the aster family includes not only plants with "aster" in their names (such as New England aster), but many other plants, too; for example:

  1. Flossflower (Ageratum houstonianum)
  2. Common chicory (Cichorium intybus)
  3. Joe-Pye weed (Eupatorium maculatum)
  4. Gayfeather or "Blazing Star" (Liatris spicata)
  5. Black-eyed Susan (Rudbeckia hirta)
  6. Blanket flower (Gaillardia x grandiflora)
  7. Hardy mums (Chrysanthemum morifolium)