August-September (this often depends on the season, if extremely dry, plants will bloom early)

Acanthus
Achillea
Alcea
Alchemilla
Anaphalis
Anemone
Asclepias
Aster
Buddlea
Caryopteris
Centranthus
Ceratostigma
Chelone
Chrysanthemum
Cimicifuga
Echinacea
Echinops
Erigeron
Eupatorium
Filipendula
Gaura
Gentiana
Grasses
Helenium
Heliopsis
Hemerocallis
Hibiscus
Kirengeshoma
Knautia
Lavatera
Lavandula
Ligularia
Lysimachia
Macleaya
Malva
Monarda
Oenothera
Origanum
Pardancanda
Pervoskia
Phlox paniculata
Physostegia
Polygonum
Ratibida
Rudbeckia
Scabiosa
Sedum
Solidago
Stokesia
Thalictrum
Tricyrtis
Veronica