Not sure where I originally found this, but it's a spreadsheet showing bloom season for many perennials. Maybe if someone out there is a gardener (or a wanna be, like me), they will appreciate this.
More than Just Lines on a Map: Best Practices for U.S Bike Routes
Perinneal Bloom Season
1. Perennial J F M A M J J A S O N D Perennial J F M A M J J A S O N D
Helleborus niger X X X X Iris, Pacific Coast X
Helleborus lividus corsicus X X Aquilegia X X
Trillium grandiflorum X X Armeria maritima X X
Euphorbia myrsinites X X X Dianthus plumarius X X
Helleborus orientalis X X X Euphorbia cyparissias X X
Lamiastrum galeobdolon X Iris pseudacorus X X
Phlox subulata X Paeonia hybrids X X
Aurinia saxatilis X X Polygonatum commutatum X X
Bergenia cordifolia X X Primula japonica X X
Brunnera macrophylla X X Stachys grandiflora X X
Euphorbia epithymoides X X Trollius europaeus X X
Iris, bearded X X Acanthus mollis X X
Mertensia virginica X X Amsonia tabernaemontana X X
Oenothera berlandieri X X Baptisia australis X X
Oenothera missouriensis X X Dicentra spectabilis X X
Oenothera speciosa X X Dictamnus albus X X
Primula sieboldii X X Thalictrum aquilegifolium X X
Primula vulgaris X X Geranium sanguineum X X X
Primula x polyantha X X Geum hybrids X X X
Pulmonaria angustifolia X X Dicentra eximia X X XX
Pulmonaria saccharata X X Hemerocallis hybrids X X XX X
Dicentra formosa X X X Dianthus deltoides X
Caltha palustris X Filipendula vulgaris X
Doronicum cordatum X Lupinus Russell hybrids X
Bloom Season of Perennials
2. Perennial J F M A M J J A S O N D Perennial J F M A M J J A S O N D
Papaver orientale X Thermopsis caroliniana X X
Salvia pratensis X Veronica incana X X
Anchusa azurea X X Achillea X X X
Aruncus dioicus X X Alchemilla mollis X X X
Asclepias tuberosa X X Campanula carpatica X X X
Astilbe X X Cimicifuga racemosa X X X
Campanula glomerata X X Lysimachia nummularia X X X
Chrysanthemum coccineum X X Monarda didyma X X X
Coreopsis grandiflora X X Scabiosa caucasica X X X
Crambe cordifolia X X Tradescantia virginiana X X X
Delphinium elatum X X Veronica hybrids X X X
Digitalis purpurea X X Veronica latifolia X X X
Filipendula rubra X X Campanula lactiflora X X X X
Filipendula ulmaria X X Chrysanthemum x superbum X X X X
Heuchera sanguinea X X Chrysogonum virginianum X X X X
Iris kaempferi X X Coreopsis lanceolata X X X X
Iris sibirica X X Dianthus caryophyllus X X X X
Lychnis chalcedonica X X Dianthus x allwoodii X X X X
Lychnis coronaria X X Gaillardia x grandiflora X X X X
Lychnis x haageana X X Kniphofia uvaria X X X X
Lysimachia punctata X X Campanula persicifolia X
Oenothera berlandieri X X Catananche caerulea X
Penstemon hartwegii X X Gypsophila X
Salvia x superba X X Hosta sieboldiana X
Bloom Season of Perennials
3. Perennial J F M A M J J A S O N D Perennial J F M A M J J A S O N D
Hosta undulata X Hibiscus moscheutos X X X
Anthemis tinctoria X X Phlox paniculata X X X
Agapanthus orientalis X X Platycodon grandiflorus X X X
Belamcanda chinensis X X Rudbeckia X X X
Chrysanthemum parthenium X X Salvia azurea X X X
Echinacea purpurea X X Boltonia asteroides X X X X
Echinops exaltatus X X Hosta fortunei X
Euphorbia corollata X X Hosta decorata X
Hosta ventricosa X X Hosta lancifolia X
Liatris X X Ligularia dentata X
Lobelia cardinalis X X Solidago hybrids X
Lysimachia clethroides X X Belamcanda flabellata X X
Lythrum salicaria X X Ceratostigma plumbaginoides X X
Stachys byzantina X X Cimicifuga foetida X X
Stachys officinalis X X Helianthus decapetalus X X
Stokesia laevis X X Hosta plantaginea X X
Thalictrum rochebrunianum X X Sedum spectabile X X
Verbascum olympicum X X Anemone x hybrida X X X
Veronica longifolia X X Aster X X X
Veronica spicata X X Cimicifuga americana X X X
Campanula pyramidalis X X X Cimicifuga dahurica X X X
Campanula rapunculoides X X X Chrysanthemum hybrids X X X X
Helenium autumnale X X X Hosta tardiflora X
Heliopsis helianthoides scabra X X X
Bloom Season of Perennials