Ragweed has no brilliant fall color; it simply balloons out to the 4’ x 4’ size. It has fern-like foliage similar to mugwort. This is the plant that makes people sneeze, not the Goldenrods! Ragweed is shallowly rooted, so you can easily remove it from the landscape before it seeds around. You’ll find it growing at edges of woods and open sunny areas, along roadsides, and sometimes among perennials in garden beds.
Goldenrods come in many shapes and sizes. The common Canada goldenrod, Solidago canadensis, has a spreading white root and an inflorescence in a broad pyramidal panicle that stretches to 4’ tall. We often plant a clumping variety called Solidago caesia, or wreath goldenrod. This is about half the height of S. canadensis and arches in a gentle way. It is tolerant of some shade.
Silverrod is the only Solidago that isn’t yellow; it is silvery-white when flowering from August through October. Its Latin name is Solidago bicolor. The flowers are evenly spaced around each stem. Look for it along roadsides and in lean soil conditions.