Quick answer: 174 native Illinois plants have a recorded bloom range that includes May.
174 species
- Adam's needle Yucca filamentosa · 21 states
- Allegheny serviceberry Amelanchier laevis · 17 states
- American alumroot Heuchera americana · 20 states
- American basswood Tilia americana · 37 states
- American beech Fagus grandifolia · 31 states
- American bittersweet Celastrus scandens · 33 states
- American bladdernut Staphylea trifolia · 28 states
- American hazelnut Corylus americana · 34 states
- American holly Ilex opaca · 28 states
- American hornbeam Carpinus caroliniana · 33 states
- American plum Prunus americana · 37 states
- American strawberry bush Euonymus americanus · 23 states
- Bearberry Arctostaphylos uva-ursi · 34 states
- Birdfoot violet Viola pedata · 34 states
- Black cherry Prunus serotina · 35 states
- Black huckleberry Gaylussacia baccata · 25 states
- Black oak Quercus velutina · 30 states
- Black tupelo Nyssa sylvatica · 31 states
- Black willow Salix nigra · 24 states
- Blackjack oak Quercus marilandica · 24 states
- Blue wild indigo Baptisia australis · 23 states
- Broadleaf cattail Typha latifolia · 39 states
- Buffalograss Bouteloua dactyloides · 19 states
- Bunchberry Cornus canadensis · 18 states
- Bur oak Quercus macrocarpa · 33 states
- Butterflyweed Asclepias tuberosa · 40 states
- Butternut Juglans cinerea · 26 states
- Canada anemone Anemone canadensis · 29 states
- Canada wild rye Elymus canadensis · 37 states
- Canada yew Taxus canadensis · 18 states
- Canadian wild ginger Asarum canadense · 30 states
- Candle anemone (thimbleweed) Anemone cylindrica · 12 states
- Cardinal flower Lobelia cardinalis · 41 states
- Carolina allspice Calycanthus floridus · 17 states
- Chinkapin oak Quercus muehlenbergii · 30 states
- Chokecherry Prunus virginiana · 44 states
- Cinnamon fern Osmunda cinnamomea · 32 states
- Climbing prairie rose Rosa setigera · 27 states
- Cockspur hawthorn Crataegus crus-galli · 25 states
- Common blue violet Viola sororia · 37 states
- Common elderberry Sambucus nigra ssp. canadensis · 36 states
- Common hackberry Celtis occidentalis · 33 states
- Common hoptree Ptelea trifoliata · 28 states
- Common ninebark Physocarpus opulifolius · 30 states
- Common persimmon Diospyros virginiana · 26 states
- Common selfheal Prunella vulgaris · 25 states
- Common winterberry Ilex verticillata · 32 states
- Common yarrow Achillea millefolium · 47 states
- Coralberry Symphoricarpos orbiculatus · 30 states
- Creeping juniper Juniperus horizontalis · 12 states
- Creeping phlox Phlox subulata · 23 states
- Crossvine Bignonia capreolata · 16 states
- Cucumbertree Magnolia acuminata · 19 states
- Deerberry Vaccinium stamineum · 22 states
- Downy hawthorn Crataegus mollis · 24 states
- Downy serviceberry Amelanchier arborea · 37 states
- Dutchman's breeches Dicentra cucullaria · 32 states
- Dwarf crested iris Iris cristata · 17 states
- Dwarf larkspur Delphinium tricorne · 15 states
- Early azalea Rhododendron prinophyllum · 17 states
- Eastern bluestar Amsonia tabernaemontana · 18 states
- Eastern hop-hornbeam Ostrya virginiana · 37 states
- Eastern leatherwood Dirca palustris · 25 states
- Eastern purple coneflower Echinacea purpurea · 24 states
- Eastern red cedar Juniperus virginiana · 37 states
- Eastern red columbine Aquilegia canadensis · 36 states
- Eastern redbud Cercis canadensis · 32 states
- Eastern white pine Pinus strobus · 28 states
- Farkleberry Vaccinium arboreum · 16 states
- Fire pink Silene virginica · 26 states
- Flowering dogwood Cornus florida · 31 states
- Foxglove beardtongue Penstemon digitalis · 35 states
- Fragrant sumac Rhus aromatica · 30 states
- Golden alexanders Zizia aurea · 35 states
- Gray alder Alnus incana · 26 states
- Gray dogwood Cornus racemosa · 19 states
- Grayhead coneflower Ratibida pinnata · 26 states
- Green ash Fraxinus pennsylvanica · 43 states
- Heart-leaved meadow parsnip Zizia aptera · 30 states
- Highbush blueberry Vaccinium corymbosum · 25 states
- Highbush cranberry Viburnum opulus var. americanum · 22 states
- Indigo bush Amorpha fruticosa · 37 states
- Jack-in-the-pulpit Arisaema triphyllum · 35 states
- Jacob's ladder Polemonium reptans · 31 states
- Lanceleaf coreopsis Coreopsis lanceolata · 35 states
- Large penstemon (shell-leaf beardtongue) Penstemon grandiflorus · 12 states
- Large-flowered bellwort Uvularia grandiflora · 27 states
- Largeflower tickseed Coreopsis grandiflora · 25 states
- Longbract wild indigo (cream false indigo) Baptisia bracteata var. leucophaea · 19 states
- Low prickly pear Opuntia humifusa · 31 states
- Lowbush blueberry Vaccinium angustifolium · 22 states
- Lyreleaf sage Salvia lyrata · 22 states
- Mapleleaf viburnum Viburnum acerifolium · 27 states
- Marsh marigold Caltha palustris · 28 states
- Mayapple Podophyllum peltatum · 35 states
- Maypop passionflower Passiflora incarnata · 21 states
- Mexican hat Ratibida columnifera · 17 states
- Mountain silverbell Halesia tetraptera · 13 states
- Nannyberry Viburnum lentago · 25 states
- Narrowleaf blue-eyed grass Sisyrinchium angustifolium · 21 states
- New Jersey tea Ceanothus americanus · 35 states
- Northern red oak Quercus rubra · 33 states
- Northern spicebush Lindera benzoin · 31 states
- Ohio buckeye Aesculus glabra · 20 states
- Old man's whiskers Geum triflorum · 9 states
- Pagoda dogwood Cornus alternifolia · 30 states
- Pale purple coneflower Echinacea pallida · 17 states
- Partridgeberry Mitchella repens · 31 states
- Pawpaw Asimina triloba · 29 states
- Pin cherry Prunus pensylvanica · 20 states
- Pin oak Quercus palustris · 27 states
- Possumhaw Ilex decidua · 17 states
- Post oak Quercus stellata · 28 states
- Prairie Junegrass Koeleria macrantha · 29 states
- Prairie blue-eyed grass Sisyrinchium campestre · 11 states
- Prairie crabapple Malus ioensis · 15 states
- Purple meadow-rue Thalictrum dasycarpum · 17 states
- Purple milkweed Asclepias purpurascens · 20 states
- Quaking aspen Populus tremuloides · 39 states
- Rattlesnake master Eryngium yuccifolium · 20 states
- Red baneberry Actaea rubra · 29 states
- Red buckeye Aesculus pavia · 15 states
- Red-osier dogwood Cornus sericea · 36 states
- Richardson's alumroot Heuchera richardsonii · 11 states
- Riverbank grape Vitis riparia · 20 states
- Rocky Mountain bee plant Peritoma serrulata · 26 states
- Royal fern Osmunda regalis var. spectabilis · 30 states
- Rusty blackhaw viburnum Viburnum rufidulum · 18 states
- Scarlet beebalm Monarda didyma · 25 states
- Scarlet oak Quercus coccinea · 28 states
- Shagbark hickory Carya ovata · 34 states
- Shingle oak Quercus imbricaria · 18 states
- Shumard oak Quercus shumardii · 22 states
- Smooth Solomon's seal Polygonatum biflorum · 34 states
- Smooth hydrangea Hydrangea arborescens · 23 states
- Smooth sumac Rhus glabra · 42 states
- Sourwood Oxydendrum arboreum · 17 states
- Southern arrowwood Viburnum dentatum · 28 states
- Southern red oak Quercus falcata · 23 states
- Spotted beebalm Monarda punctata · 29 states
- Starry false Solomon's seal Maianthemum stellatum · 19 states
- Sugar maple Acer saccharum · 34 states
- Sundial lupine Lupinus perennis · 28 states
- Swamp rose Rosa palustris · 27 states
- Swamp white oak Quercus bicolor · 23 states
- Sweet crabapple Malus coronaria · 20 states
- Sweet-fern Comptonia peregrina · 21 states
- Sweetgum Liquidambar styraciflua · 26 states
- Three-flower melic grass Melica nitens · 17 states
- Trailing arbutus Epigaea repens · 24 states
- Tulip tree Liriodendron tulipifera · 27 states
- Twinleaf Jeffersonia diphylla · 15 states
- Twoleaf miterwort Mitella diphylla · 25 states
- Virginia bluebells Mertensia virginica · 23 states
- Virginia creeper Parthenocissus quinquefolia · 40 states
- Virginia iris Iris virginica · 26 states
- Virginia spiderwort Tradescantia virginiana · 24 states
- Virginia springbeauty Claytonia virginica · 28 states
- Virginia strawberry Fragaria virginiana · 30 states
- Virginia sweetspire Itea virginica · 19 states
- Water oak Quercus nigra · 17 states
- White ash Fraxinus americana · 35 states
- White baneberry Actaea pachypoda · 33 states
- White oak Quercus alba · 33 states
- White wild indigo Baptisia alba · 23 states
- Whorled milkweed Asclepias verticillata · 30 states
- Wild blue phlox Phlox divaricata · 36 states
- Wild geranium Geranium maculatum · 33 states
- Wild hyacinth (Atlantic camas) Camassia scilloides · 20 states
- Willow oak Quercus phellos · 23 states
- Winecup Callirhoe involucrata · 16 states
- Woodland pinkroot Spigelia marilandica · 16 states
- Yellow birch Betula alleghaniensis · 21 states
- Yellow buckeye Aesculus flava · 14 states
May in an Illinois native garden
May is Illinois's peak bloom month: 174 of the state's 289 native plants in this directory flower in May, more than in any other month.
45 start blooming in May, including American bittersweet, American strawberry bush and Black huckleberry. 54 finish in May, including American beech, American hornbeam and Black oak, so this is the last chance to see them in flower.
111 of them grow in full or partial sun and 122 tolerate shade, so there are options for open beds and woodland edges alike. Sizes run from low plants like American alumroot and Birdfoot violet to trees such as Allegheny serviceberry and American basswood. For wildlife, 129 support pollinators, 105 provide food or cover for birds and 63 are caterpillar host plants.
142 of the 174 have a seed or plant listing we verified as the wild species. Be careful buying American alumroot, Common yarrow, Creeping phlox: 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.
- Chokecherry Prunus virginiana · Sun, Part Shade, Shade · blooms Apr-Jul
- Green ash Fraxinus pennsylvanica · Sun, Part Shade, Shade · blooms Apr-Jun
- Smooth sumac Rhus glabra · Sun, Part Shade, Shade · blooms May-Aug