For a fabulous late summer to fall combination pair the striking blue flowers of hardy ageratum with the bright yellow flowers of ‘Fireworks’ goldenrod. ‘Fireworks appears in spring with light green buds that persist all summer while hardy ageratum follows a bit later. In late summer the two burst into bloom with their complementary colors just as other plants are beginning to taper off. Both plants feature fuzzy flowers but ‘Fireworks’ carries them all over its long slender stems while hardy ageratum carries them in dense heads. The shiny silvery seed heads of ‘Fireworks’ continue to add interest after the flowers fade. Both plants do well in moist well-drained soil in full sun and attract butterflies.
Hardy Ageratum (Eupatorium coelestinum)
These rhizomatious perennials native to eastern US where it is found in moist soils along streams, ponds and other bodies of water. It bear dense corymbs of tiny azure blue flowers that are similar to those of annual ageratum. Plants can look weedy but develop more lateral shoots if cut back once or twice during the summer.
Bloom Time: Late summer into fall
Size: 2-3’ H 3’ W
Hardiness: Zones 6-10
‘Fireworks’ Golden Rod (Solidago rugosa ‘Fireworks’)
Slender cascading stems bearing fluffy yellow flowers over a long bloom period. ‘Fireworks’ is less invasive than other goldenrods and likes moister soil. Flowers are attractive to bees as well as butterflies.
Bloom Time: Late summer into fall
Size: 2.5-3’ H x 2/5-3’ W
Hardiness: 4-8