Flowers to Plant in Pennsylvania

Pennsylvania gardeners gravitate toward a handful of flowers that consistently outsell alternatives in regional nurseries. The current top five for Pennsylvania are Mountain Laurel, Black-eyed Susan, Hosta, Daylily, New England Aster. Each is well-adapted to Pennsylvania's combination of climate, soil, and seasonal rainfall — and each appears on regional best-seller lists year after year.

The list above isn't the same as what you'd see in Ohio or Oregon — and that regional difference matters more than most homeowners realize. A flower that thrives in Pennsylvaniamay struggle two states over because of soil pH, summer humidity, winter chill hours, or photoperiod. When you're choosing flowers, regional bestsellers are the highest-confidence starting point. Branch into less common species after you've confirmed that the regional staples actually perform in your specific yard.

Pennsylvania's fall display is among the country's best — cool nights and gradual frost progression deliver vivid color in mums, asters, and ornamental kale. First frost ranges from mid-September in the highest mountain counties to mid-October in Philadelphia and the southeast. Plant pansies and ornamental kale in early September for color until frost. Native New England aster, goldenrod, and white snakeroot bloom from late summer through fall and feed migrating monarchs at peak nectar demand. Hellebores bloom in late winter for very early-season color.

Fall blooms extend the Pennsylvania flower season well past the summer peak. Garden chrysanthemums (mums) are the headline fall flower across all US zones — plant nursery-pot mums in early September for immediate color, or plant garden mums in spring for established perennials that return reliably each fall. Asters provide the second wave of fall color, with native New England aster (Symphyotrichum novae-angliae) and New York aster blooming September through October in Pennsylvania gardens.

For continuous color into late fall and winter, cool-season annuals like pansies, violas, snapdragons, and ornamental kale tolerate frost down to -7°C (20°F) and bloom through the first hard freeze. In Pennsylvania, plant cool-season annuals in late August or early September for color through November and again in early spring before warm-season annuals can be set out. Sedum 'Autumn Joy' and ornamental grasses (switchgrass, little bluestem, miscanthus) provide structural fall interest with seedheads and foliage that persist through winter.

For winter interest beyond annuals, consider hellebores (Lenten roses) for shaded Pennsylvania gardens — these evergreen perennials bloom February through April even in moderate winters. Witch hazel, winter jasmine, and red-twig dogwood add structural color to winter gardens. In Pennsylvania's cold winters, focus on plants with winter-persistent seedheads, evergreen foliage, and bark color rather than active winter blooms. Plan your fall and winter garden layout in spring when nurseries stock the widest selection of fall-blooming and winter-interest plants.

Pennsylvania soils trend acidic (pH 4.5–5.5) across most of the state, with notable regional variation: limestone-influenced soils in the Cumberland Valley and Lebanon Valley have higher pH (6.5–7.5); the rest of the state has more typical Appalachian acidic soils. Soils are often rocky, especially in the mountain and ridge-and-valley regions. Most Pennsylvania gardens benefit from lime applications (based on soil test) to bring pH up to 6.0–6.5 for better nutrient availability. Organic matter is the standard universal amendment.

Soil quality is the single biggest factor in Pennsylvania garden success — and Pennsylvania's soil varies dramatically by region. Test your soil before amending: a basic soil test from your county extension office or a home test kit reveals pH (target 6.0 to 7.0 for most flowers), texture (sand vs silt vs clay), and key nutrient levels. Most flower problems traced to 'planting wrong' actually originate with unsuitable soil that no amount of right-time planting can overcome.

For heavy clay soils common in many Pennsylvania regions, amend the planting bed with 5 to 10 cm (2 to 4 inches) of compost worked into the top 30 cm (12 inches). Avoid sand alone in clay — sand mixed with clay produces concrete-like results. Pumice or expanded shale work better as a structural amendment. For sandy soils, the same compost amendment improves moisture retention and nutrient holding capacity. For neutral loam soils (the easiest case), light compost amendment is sufficient maintenance — no major restructuring needed.

Adjust pH only if soil testing confirms a problem. Most flowers prefer slightly acidic to neutral soil (pH 6.0 to 7.0). For acidic soils below 5.5, apply garden lime in fall for spring planting. For alkaline soils above 7.5, apply elemental sulfur in fall — pH adjustment with sulfur takes 6 to 12 months to fully take effect. Hydrangeas are the major exception: bigleaf hydrangeas bloom blue in acidic soil (below pH 5.5) and pink in alkaline soil (above pH 6.5), so adjust accordingly for desired color.

Time your bed preparation to your Pennsylvania climate. In Pennsylvania's moderate climate, fall prep for spring planting is ideal, but you can also prep beds 2 to 4 weeks before planting if needed. Spring prep limits how much soil amendment you can incorporate without disturbing planting. Add 5 cm (2 inches) of mulch after planting to retain moisture and suppress weeds — shredded bark, pine needles (in acid-loving beds), or composted leaves all work well.

Pennsylvania hosts one of the eastern US's most important monarch migration corridors — the Allegheny Front and the Susquehanna River valley funnel monarchs through during fall migration in September. Plant native common milkweed, butterfly weed, and swamp milkweed to support breeding monarchs. Pennsylvania's mountain counties support multiple at-risk bumble bee species, including the rusty-patched bumble bee. Plant native bee balm (Monarda didyma), wild bergamot, and Joe Pye weed to support native bumble bee populations. Ruby-throated hummingbirds are common breeders statewide; plant cardinal flower (Lobelia cardinalis), trumpet honeysuckle, and salvias to support them through migration and breeding.

Pennsylvania gardens support a remarkable diversity of native pollinators — bees, butterflies, moths, hummingbirds, and beneficial flies — when planted with the right mix of flowering plants. The 2024 University of Delaware research by Doug Tallamy documented that native plants support 4 to 35 times more native insect species than introduced ornamentals — and native insects are the foundation of native bird food webs. Choosing flowers with high pollinator value pays dividends well beyond aesthetic appeal.

Top pollinator flowers for Pennsylvania gardens include native coneflower (Echinacea purpurea), black-eyed Susan (Rudbeckia hirta), bee balm (Monarda), butterfly weed (Asclepias tuberosa), wild bergamot, native asters, goldenrod, and native sunflowers. Lavender, salvia, catmint, and zinnia are excellent non-native choices for honeybees and a wide range of native bee species. For hummingbirds, plant tubular red and orange flowers — cardinal flower, trumpet honeysuckle, salvia, and bee balm. For night-flying pollinator moths, plant evening-fragrant flowers like moonflower, evening primrose, and night-blooming jasmine.

Milkweed (Asclepias) is the single most important plant for monarch butterfly conservation — monarchs lay eggs only on milkweed, and milkweed is the sole food source for monarch caterpillars. Pennsylvania sits in the monarch migration range, and planting native milkweed species (butterfly weed, swamp milkweed, common milkweed) directly supports monarch reproduction. Native milkweed species naturally die back in fall, supporting the monarch migration cycle. Avoid mowing or cutting back milkweed plantings until late spring to support overwintering populations of beneficial insects.

Design your Pennsylvania pollinator garden around bloom succession — plant species that bloom in different windows so something is always flowering from April through October. Early-spring bloomers (crocus, hellebore, native willow) feed emerging queen bees. Late-summer and fall bloomers (goldenrod, native asters, sedum) provide critical pre-migration fuel for monarchs and overwintering food for native bees. Cluster plantings of 3 to 5 of the same species together — pollinators forage more efficiently on patches than on scattered single plants. Skip pesticides entirely on pollinator plantings; even organic-approved insecticides like spinosad and pyrethrin are toxic to bees and butterflies. Hand-removing pests or accepting some leaf damage is the right approach in pollinator-friendly gardens.