Quick answer: 64 native Colorado plants have a recorded bloom range that includes May.
64 species
- Alderleaf mountain mahogany Cercocarpus montanus · 15 states
- American plum Prunus americana · 37 states
- Antelope bitterbrush Purshia tridentata · 12 states
- Apache plume Fallugia paradoxa · 8 states
- Arrowleaf balsamroot Balsamorhiza sagittata · 12 states
- Banana yucca Yucca baccata · 8 states
- Bearberry Arctostaphylos uva-ursi · 34 states
- Blackfoot daisy Melampodium leucanthum · 6 states
- Bluebunch wheatgrass Pseudoroegneria spicata · 16 states
- Broadleaf cattail Typha latifolia · 39 states
- Buffalograss Bouteloua dactyloides · 19 states
- Butterflyweed Asclepias tuberosa · 40 states
- Canada anemone Anemone canadensis · 29 states
- Canada wild rye Elymus canadensis · 37 states
- Cardinal flower Lobelia cardinalis · 41 states
- Chocolate flower Berlandiera lyrata · 6 states
- Chokecherry Prunus virginiana · 44 states
- Colorado four o'clock Mirabilis multiflora · 7 states
- Common elderberry Sambucus nigra ssp. canadensis · 36 states
- Common hackberry Celtis occidentalis · 33 states
- Common ninebark Physocarpus opulifolius · 30 states
- Common yarrow Achillea millefolium · 47 states
- Creeping Oregon grape Mahonia repens · 15 states
- Creeping juniper Juniperus horizontalis · 12 states
- Douglas fir Pseudotsuga menziesii · 12 states
- Gambel oak Quercus gambelii · 8 states
- Gray alder Alnus incana · 26 states
- Green ash Fraxinus pennsylvanica · 43 states
- Greenleaf manzanita Arctostaphylos patula · 9 states
- Highbush cranberry Viburnum opulus var. americanum · 22 states
- Idaho fescue Festuca idahoensis · 12 states
- Indian blanket Gaillardia pulchella · 17 states
- Indian ricegrass Achnatherum hymenoides · 17 states
- Indigo bush Amorpha fruticosa · 37 states
- Lewis flax (blue flax) Linum lewisii · 17 states
- Mexican hat Ratibida columnifera · 17 states
- Mule's ears Wyethia amplexicaulis · 8 states
- Munro's globemallow Sphaeralcea munroana · 9 states
- Oceanspray Holodiscus discolor · 9 states
- Ponderosa pine Pinus ponderosa · 16 states
- Prairie Junegrass Koeleria macrantha · 29 states
- Quaking aspen Populus tremuloides · 39 states
- Red baneberry Actaea rubra · 29 states
- Red-osier dogwood Cornus sericea · 36 states
- Rocky Mountain bee plant Peritoma serrulata · 26 states
- Rocky Mountain iris Iris missouriensis · 11 states
- Rocky Mountain penstemon Penstemon strictus · 5 states
- Saskatoon serviceberry Amelanchier alnifolia · 14 states
- Scarlet globemallow Sphaeralcea coccinea · 12 states
- Seep monkeyflower Erythranthe guttata · 15 states
- Showy milkweed Asclepias speciosa · 17 states
- Silver buffaloberry Shepherdia argentea · 17 states
- Smooth sumac Rhus glabra · 42 states
- Snowbrush ceanothus Ceanothus velutinus · 10 states
- Spotted beebalm Monarda punctata · 29 states
- Tufted evening primrose Oenothera caespitosa · 15 states
- Upland larkspur Delphinium nuttallianum · 13 states
- Utah serviceberry Amelanchier utahensis · 5 states
- Virginia creeper Parthenocissus quinquefolia · 40 states
- Western yarrow Achillea millefolium var. occidentalis · 18 states
- Winecup Callirhoe involucrata · 16 states
- Winterfat Krascheninnikovia lanata · 12 states
- Woolly paperflower Psilostrophe tagetina · 7 states
- Wyoming Indian paintbrush Castilleja linariifolia · 9 states
May in a Colorado native garden
May is one of Colorado's busiest bloom months, with 64 of the state's 100 native plants flowering (the peak is June).
25 start blooming in May, including Apache plume, Bluebunch wheatgrass and Butterflyweed. 7 finish in May, including Alderleaf mountain mahogany, Common hackberry and Creeping juniper, so this is the last chance to see them in flower.
54 of them grow in full or partial sun and 22 tolerate shade, so there are options for open beds and woodland edges alike. Sizes run from low plants like Arrowleaf balsamroot and Bluebunch wheatgrass to trees such as Alderleaf mountain mahogany and American plum. For wildlife, 47 support pollinators, 32 provide food or cover for birds and 16 are caterpillar host plants.
44 of the 64 have a seed or plant listing we verified as the wild species. Be careful buying Apache plume, Common yarrow, Indian blanket: 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