These North American natives are not as widely grown as they deserve, largely due to the mistaken belief that their pollen causes hay fever (in fact, other plants are responsible). Although a few of the hundred-plus species are weeds in many regions, many are choice garden plants. All have leafy stems rising from tough, woody, spreading rootstocks; all bear small yellow flowers in large, branching, typically one-sided clusters from mid- or late summer into fall. Good cut flowers. These are tough plants that thrive in not-too-rich soil. Use in borders with black-eyed Susan (Rudbeckia hirta) or Michaelmas daisy (Aster novi-belgii), or naturalize in meadows. Butterflies are attracted to goldenrod flowers, and birds enjoy the seeds.
S. altissima (S. canadensis scabra). TALL GOLDENROD. The state flower of Kentucky, this is a stiff, erect, much-branched plant to 37 ft. tall, 112 ft. wide. Every part of it is bristly. Bears large, branched, pyramidal flower heads. Clumping growth.
S. caesia. BLUE-STEMMED GOLDENROD, WREATH GOLDENROD. Grows 1123 ft. tall, with arching, downy, blue-green stems loaded with blooms. Clumping growth.
S. canadensis. CANADA GOLDENROD. Stands 35 ft. tall, 3 ft. wide. Large, showy flower panicles, densely packed with blossoms. Robust and vigorous, spreading widely by underground runners; can be invasive.
S. hybrids. The following are among the best garden selections. All form slowly spreading, manageable clumps.
'Cloth of Gold'. To 112 ft. tall, 1 ft. wide, with a long bloom season beginning in midsummer.
'Crown of Rays'. To 23 ft. tall, 12 ft. wide. Stiff and erect, with flattish flower clusters.
'Golden Baby' (Goldkind'). To 2 ft. high, 112 ft. wide, with plumelike flower clusters.
'Goldenmosa'. To 2123 ft. tall, 112 ft. wide, with very large flower clusters reminiscent of florist's mimosa (Acacia baileyana).
'Gold Spangles'. To 2212 ft. high, 1112 ft. wide. Leaves are splashed with gold and green. Showy plumes of fragrant bright yellow flowers. A bit of a spreader; divide every two to three years to keep in bounds.
'Laurin'. Vigorous dwarf selection to 1112 ft. high and about as wide. Looks refined.
'Little Lemon' ('Dansolitlem'). Upright, dense dwarf to just 14 in. high, 18 in. wide. Soft yellow flowers.
S. nemoralis. GRAY GOLDENROD. Tidy-looking plant ranging from 6 in. to 2 ft. tall and wide. Soft, gray-green basal leaves; curved flower plumes in rich yellow. Blooms over a longer period than most species. Likes dryish soil. Short lived; best treated as a biennial. Deadhead to prevent prolific self-seeding.
S. odora. SWEET GOLDENROD. Tall grower to 612 ft. high, 3 ft. wide. Unbranched stems are set with anise-scented leaves. Large, long-lasting flower heads. Particularly tolerant of poor, dry soils. Clumping growth.
S. rigida. STIFF GOLDENROD. To 112212 ft. wide, with stems 25 ft. high. Dense golden blossom heads. Very adaptable to garden conditions; takes average or rich soil, much or little moisture. Moderately vigorous spreader.
S. rugosa. ROUGH-LEAFED GOLDENROD. Hairy-stemmed plant to 5 ft. tall, 3 ft. wide, with arching, widely branching stems. 'Fireworks' makes a more compact clump (3 ft. tall, 2 ft. wide). Clumping.
S. sempervirens. SEASIDE GOLDENROD. Stately clumping species to 8 ft. tall, 112 ft. wide. Tolerates dry soil, heat, salt, wind. May topple in rich soil. Spoon-shaped basal leaves.
S. shortii. 'Solar Cascade'. Grows 2212 ft. tall and 2 ft. wide, with gracefully arching stems. Good ground cover. Clumping growth.
S. speciosa. SHOWY GOLDENROD. Upright growth to 24 ft. tall and wide, with erect, densely packed flower heads. Very showy. Clumping.
S. sphacelata 'Golden Fleece'. Stands just 1122 ft. high when in bloom. Low foliage mound makes it a good ground cover; if you set plants 15 in. apart, spreading growth will give you a solid mat in just a year.