Quick answer: 45 native Ohio plants have a recorded bloom range that includes August.
45 species
- American bellflower Campanulastrum americanum · 19 states
- Arctic brome (Kalm's brome) Bromus kalmii · 5 states
- Big bluestem Andropogon gerardii · 25 states
- Black-eyed Susan Rudbeckia hirta · 42 states
- Blue mistflower Conoclinium coelestinum · 26 states
- Brown-eyed Susan Rudbeckia triloba · 6 states
- Butterflyweed Asclepias tuberosa · 37 states
- Cardinal flower Lobelia cardinalis · 37 states
- Common buttonbush Cephalanthus occidentalis · 23 states
- Common yarrow Achillea millefolium · 31 states
- Crimson-eyed rose-mallow Hibiscus moscheutos · 14 states
- Cup plant Silphium perfoliatum · 17 states
- Cutleaf coneflower Rudbeckia laciniata · 21 states
- Dense blazing star Liatris spicata · 15 states
- Eastern purple coneflower Echinacea purpurea · 22 states
- Eastern wahoo Euonymus atropurpureus · 2 states
- Fall obedient plant Physostegia virginiana · 21 states
- Fewleaf sunflower Helianthus occidentalis · 1 states
- Fireweed Chamerion angustifolium · 28 states
- Great blue lobelia Lobelia siphilitica · 32 states
- Harebell Campanula rotundifolia · 25 states
- Hollow Joe-pye weed Eutrochium fistulosum · 14 states
- Indiangrass Sorghastrum nutans · 19 states
- Jerusalem artichoke Helianthus tuberosus · 9 states
- Little bluestem Schizachyrium scoparium · 23 states
- Mapleleaf viburnum Viburnum acerifolium · 5 states
- New England aster Symphyotrichum novae-angliae · 18 states
- New Jersey tea Ceanothus americanus · 31 states
- Partridgeberry Mitchella repens · 17 states
- Pearly everlasting Anaphalis margaritacea · 18 states
- Prairie dropseed Sporobolus heterolepis · 11 states
- Rocky Mountain bee plant Peritoma serrulata · 22 states
- Scaly blazing star Liatris squarrosa · 5 states
- Scarlet beebalm Monarda didyma · 18 states
- Showy tick trefoil Desmodium canadense · 21 states
- Shrubby cinquefoil Dasiphora fruticosa ssp. floribunda · 15 states
- Sideoats grama Bouteloua curtipendula · 25 states
- Smooth sumac Rhus glabra · 34 states
- Sourwood Oxydendrum arboreum · 14 states
- Swamp rose Rosa palustris · 11 states
- Sweet Joe-Pye Eutrochium purpureum · 17 states
- Switchgrass Panicum virgatum · 24 states
- Trumpet vine Campsis radicans · 24 states
- White meadowsweet Spiraea alba · 8 states
- Winged sumac Rhus copallinum · 11 states