Quick answer: 103 native Illinois plants have a recorded bloom range that includes August.
103 species
- Adam's needle Yucca filamentosa · 21 states
- American alumroot Heuchera americana · 20 states
- American bellflower Campanulastrum americanum · 34 states
- Arctic brome (Kalm's brome) Bromus kalmii · 15 states
- Big bluestem Andropogon gerardii · 41 states
- Black-eyed Susan Rudbeckia hirta · 44 states
- Blue grama Bouteloua gracilis · 19 states
- Blue mistflower Conoclinium coelestinum · 32 states
- Blue vervain Verbena hastata · 34 states
- Brown-eyed Susan Rudbeckia triloba · 21 states
- Buffalograss Bouteloua dactyloides · 19 states
- Bunchberry Cornus canadensis · 18 states
- Butterflyweed Asclepias tuberosa · 40 states
- Canadian burnet Sanguisorba canadensis · 20 states
- Cardinal flower Lobelia cardinalis · 41 states
- Closed bottle gentian Gentiana andrewsii · 23 states
- Common buttonbush Cephalanthus occidentalis · 29 states
- Common evening primrose Oenothera biennis · 30 states
- Common selfheal Prunella vulgaris · 25 states
- Common sneezeweed Helenium autumnale · 40 states
- Common yarrow Achillea millefolium · 47 states
- Compass plant Silphium laciniatum · 20 states
- Crimson-eyed rose-mallow Hibiscus moscheutos · 28 states
- Culver's root Veronicastrum virginicum · 32 states
- Cup plant Silphium perfoliatum · 27 states
- Cutleaf coneflower Rudbeckia laciniata · 43 states
- Dense blazing star Liatris spicata · 24 states
- Devil's walking stick Aralia spinosa · 21 states
- Dotted blazing star Liatris punctata · 17 states
- Eastern purple coneflower Echinacea purpurea · 24 states
- Eastern teaberry Gaultheria procumbens · 23 states
- Fall obedient plant Physostegia virginiana · 37 states
- Fewleaf sunflower Helianthus occidentalis · 16 states
- Fire pink Silene virginica · 26 states
- Fireweed Chamerion angustifolium · 37 states
- Flowering spurge Euphorbia corollata · 29 states
- Golden alexanders Zizia aurea · 35 states
- Grayhead coneflower Ratibida pinnata · 26 states
- Great blue lobelia Lobelia siphilitica · 36 states
- Groundnut Apios americana · 21 states
- Harebell Campanula rotundifolia · 35 states
- Hollow Joe-pye weed Eutrochium fistulosum · 24 states
- Indiangrass Sorghastrum nutans · 37 states
- Inland sea oats Chasmanthium latifolium · 21 states
- Jerusalem artichoke Helianthus tuberosus · 26 states
- King of the meadow Thalictrum pubescens · 21 states
- Little bluestem Schizachyrium scoparium · 42 states
- Mapleleaf viburnum Viburnum acerifolium · 27 states
- Maypop passionflower Passiflora incarnata · 21 states
- Mexican hat Ratibida columnifera · 17 states
- Michigan lily Lilium michiganense · 16 states
- New England aster Symphyotrichum novae-angliae · 29 states
- New Jersey tea Ceanothus americanus · 35 states
- Northern bush honeysuckle Diervilla lonicera · 18 states
- Ontario blazing star Liatris cylindracea · 8 states
- Orange coneflower Rudbeckia fulgida · 23 states
- Partridge pea Chamaecrista fasciculata · 30 states
- Partridgeberry Mitchella repens · 31 states
- Pearly everlasting Anaphalis margaritacea · 38 states
- Prairie blazing star Liatris pycnostachya · 19 states
- Prairie dropseed Sporobolus heterolepis · 19 states
- Prairie ironweed Vernonia fasciculata · 14 states
- Prairie tickseed Coreopsis palmata · 10 states
- Purple prairie clover Dalea purpurea · 18 states
- Rattlesnake master Eryngium yuccifolium · 20 states
- Rocky Mountain bee plant Peritoma serrulata · 26 states
- Roundhead lespedeza Lespedeza capitata · 30 states
- Scaly blazing star Liatris squarrosa · 22 states
- Scarlet beebalm Monarda didyma · 25 states
- Sensitive fern Onoclea sensibilis · 26 states
- Showy goldenrod Solidago speciosa · 28 states
- Showy tick trefoil Desmodium canadense · 29 states
- Shrubby St. John's-wort Hypericum prolificum · 33 states
- Shrubby cinquefoil Dasiphora fruticosa ssp. floribunda · 23 states
- Sideoats grama Bouteloua curtipendula · 38 states
- Smooth hydrangea Hydrangea arborescens · 23 states
- Smooth oxeye Heliopsis helianthoides · 30 states
- Smooth rose Rosa blanda · 17 states
- Smooth sumac Rhus glabra · 42 states
- Sourwood Oxydendrum arboreum · 17 states
- Spotted beebalm Monarda punctata · 29 states
- Steeplebush Spiraea tomentosa · 22 states
- Swamp milkweed Asclepias incarnata · 37 states
- Swamp rose Rosa palustris · 27 states
- Swamp sunflower Helianthus angustifolius · 21 states
- Sweet Joe-Pye Eutrochium purpureum · 33 states
- Sweet coneflower Rudbeckia subtomentosa · 11 states
- Sweet-fern Comptonia peregrina · 21 states
- Switchgrass Panicum virgatum · 43 states
- Tall blazing star Liatris aspera · 26 states
- Trumpet vine Campsis radicans · 33 states
- Virgin's bower Clematis virginiana · 27 states
- Virginia chain fern Woodwardia virginica · 24 states
- Virginia mountain mint Pycnanthemum virginianum · 27 states
- Virginia spiderwort Tradescantia virginiana · 24 states
- White meadowsweet Spiraea alba · 22 states
- White snakeroot Ageratina altissima · 23 states
- White turtlehead Chelone glabra · 22 states
- Wholeleaf rosinweed Silphium integrifolium · 16 states
- Whorled milkweed Asclepias verticillata · 30 states
- Winged sumac Rhus copallinum · 30 states
- Wood lily Lilium philadelphicum · 28 states
- Yellow passionflower Passiflora lutea · 21 states
August in an Illinois native garden
August is a quieter month in Illinois: 103 of the state's 289 native plants flower in August, compared with 174 at the May peak. That makes these plants valuable for keeping color, and food for pollinators, going outside the main season.
12 start blooming in August, including Big bluestem, Closed bottle gentian and Dotted blazing star. 26 finish in August, including Adam's needle, American alumroot and American bellflower, so this is the last chance to see them in flower.
77 of them grow in full or partial sun and 45 tolerate shade, so there are options for open beds and woodland edges alike. Sizes run from low plants like American alumroot and Black-eyed Susan to trees such as Devil's walking stick and Maypop passionflower. For wildlife, 93 support pollinators, 59 provide food or cover for birds and 35 are caterpillar host plants.
87 of the 103 have a seed or plant listing we verified as the wild species. Be careful buying American alumroot, Black-eyed Susan, Common yarrow: common listings for these are often a bred variety or a different species.
Good places to start
Verified wild-species listings that take sun and are widely native, so they are forgiving first plants.
- Cutleaf coneflower Rudbeckia laciniata · Sun, Part Shade, Shade · blooms Jul-Oct
- Little bluestem Schizachyrium scoparium · Sun, Part Shade · blooms Jun-Dec
- Smooth sumac Rhus glabra · Sun, Part Shade, Shade · blooms May-Aug