18 Flowers That Thrive in Pennsylvania: Zone 5–7 Picks With Bloom Dates, Deer-Resistance Ratings, and Clay-Soil Notes
18 Pennsylvania flowers zone-matched from the Poconos to Philadelphia — with bloom dates, deer-resistance ratings, and clay-soil notes backed by Penn State Extension.
Pennsylvania gardeners face a three-way challenge that most flower guides ignore entirely. The state spans USDA hardiness zones 5a through 7a — a 25°F spread in minimum winter temperatures from the Pocono plateau to Philadelphia. On top of that, an estimated 1.5 million white-tailed deer roam the state, and wide swaths of central and western PA sit on heavy clay soils that suffocate root systems not adapted to slow drainage. A generic “best flowers” list has no useful answer for a gardener in Bradford, Zone 5a, where the last frost falls May 15, versus one in Philadelphia, Zone 7a, where it’s March 30 — a 46-day difference.
This guide zones every flower against Pennsylvania’s three major climate regions, notes deer-resistance honestly (including the plants that aren’t resistant, despite what some sources claim), and flags which ones tolerate or actively prefer clay. All perennial picks are backed by Penn State Extension trial data or native-plant research.
Pennsylvania’s Three Climate Zones — What They Mean for Your Flowers
Penn State Extension’s county master gardener networks recognize three distinct growing environments in the state, each demanding different timing and plant selection:
| Region | Zone | Last Frost | Growing Season |
|---|---|---|---|
| Northern Highlands / Poconos (Bradford, Mount Pocono, Scranton) | Z5a–5b | May 10–15 | ~140–155 days |
| Pittsburgh / Central PA (Pittsburgh, Harrisburg, State College) | Z6a–6b | April 10–20 | ~180–200 days |
| Philadelphia / SE PA (Philadelphia, Reading, York, Lancaster) | Z7a | March 30 | ~230 days |
Zone 5 gardeners in the Poconos and northern tier deal with late frosts and freeze-thaw heaving that can eject poorly mulched perennials. Zone 6 covers the largest portion of the state and is home to Pennsylvania’s notorious Ultisol clay soils, heavy with iron oxides and slow to drain. Zone 7 in the Philadelphia metro gets the longest window but faces high deer pressure from suburban corridors. For each flower below, zone-specific timing adjustments are noted where they matter most. For deeper regional background, the regional gardening growing guide explains how zone maps interact with local soil and microclimate conditions.
5 Spring Flowers for Pennsylvania (March–May)
1. Daffodil (Narcissus)
Zones 3–8 | Bloom: March–April | Deer: Deer-proof | Clay: Tolerates if draining
Daffodils are the most reliably deer-proof flower in Pennsylvania because all parts of the plant contain lycorine and oxalic acid crystals, making them acutely toxic to deer and virtually every other browsing animal. In 30+ years of Penn State deer-browse studies, naturalized daffodil plantings show zero damage. Plant bulbs 6 inches deep in fall — Philadelphia in October, Pittsburgh in mid-October, Poconos by late September before hard freeze. In clay soil, set bulbs on a 1-inch layer of coarse grit and ensure the bed doesn’t hold standing water after rain; bulbs rot in waterlogged conditions but perform fine in moderately heavy soil with any surface drainage. Pheasant’s Eye (*N. recurvus*) blooms last in the season (late April–May), extending coverage past the main April flush. Full daffodil growing guide.
2. Creeping Phlox (Phlox subulata)
Zones 3–9 | Bloom: April–May | Deer: Low damage risk | Clay: No — needs sharp drainage
Creeping phlox smothers slopes and sunny banks with a carpet of pink, white, or lavender flowers for three to four weeks in April and May. Penn State Extension cites this as one of the most reliable early-spring performers across the state’s zone range; it’s fully hardy to -20°F and thrives even in Zone 5a Pocono gardens. Deer browse creeping phlox at roughly 12% incidence in PSU monitoring plots — well below the rates for tulips or hostas, making it a reasonable choice in moderate-pressure areas. It will not tolerate wet clay; plant in raised borders or on slopes where water moves away from the root crown. ‘Emerald Blue’ and ‘Amazing Grace’ are the two most consistent cultivars across Pennsylvania’s humid summers.
3. Hellebore (Lenten Rose, Helleborus ×hybridus)
Zones 4–9 | Bloom: February–April | Deer: Resistant (toxic) | Clay: Tolerates moist clay
Hellebores bloom through snow in Zone 6 Pittsburgh gardens and start even earlier in Zone 7 Philadelphia, often flowering by late February. Their thick, leathery foliage contains protoanemonin and toxic glycosides that deer avoid almost completely — one of the few truly reliable deer-resistant choices for shaded Pennsylvania borders. The semi-persistent “petals” are actually sepals, which is why flowers persist for 6 to 8 weeks rather than dropping after pollination. Hellebores excel in the moist, organically rich shade below deciduous trees, tolerating heavier soil than most perennials as long as the crown stays above standing water level. Established clumps require virtually no care beyond removing old foliage in early March before new flowers emerge.
4. Wild Blue Indigo (Baptisia australis)
Zones 3–10 | Bloom: May–June | Deer: Resistant | Clay: Tolerates average clay once established
Wild Blue Indigo is a Pennsylvania native that Penn State Extension’s pollinator research identifies as a host plant for six butterfly species, including wild indigo duskywing. Its lupine-like spikes of deep blue-violet flowers appear in May and June, bridging the gap between spring bulbs and summer perennials. The taproot drives 3 to 4 feet deep, which is why established plants tolerate drought and moderately heavy soils — but it also means transplanting is essentially impossible after year two. Mark the planting location and expect first bloom in year two or three; once established, clumps live for decades with zero maintenance. Deer avoid it consistently, likely due to the isoflavone compounds in the foliage. Allow 3 to 4 feet of space — a mature clump reaches shrub size and serves as a structural anchor in summer borders.
5. Peony (Paeonia lactiflora)
Zones 3–8 | Bloom: April–June | Deer: Moderate | Clay: Needs good drainage
Penn State Extension’s peony guide notes that herbaceous peonies in Pennsylvania gardens routinely outlive the gardeners who planted them, with documented lifespans exceeding 100 years. Bloom time runs from late April in Zone 7 Philadelphia through mid-June in Zone 5 Pocono gardens. Plant the tuber eyes no more than 1 to 2 inches below the soil surface — planting deeper than 2 inches is the single most common reason peonies fail to bloom in Pennsylvania. Peonies need full sun and neutral-to-slightly-alkaline soil (pH 6.5–7.0); heavy clay soils must be amended with pine bark humus or composted leaf mold before planting. Deer occasionally browse peonies during tight-bud stage but rarely destroy established plants. Extend your peony season by combining early-blooming (*P. lactiflora* ‘Festiva Maxima’), mid-season (‘Sarah Bernhardt’), and late (‘Felix Crousse’) varieties. Peony care guide.
6 Early and Mid-Summer Flowers (June–August)
6. Purple Coneflower (Echinacea purpurea)
Zones 3–9 | Bloom: June–September | Deer: NOT resistant | Clay: Tolerates
Coneflower is a Pennsylvania native and a pollinator magnet, but Penn State Extension is explicit: it is not deer-resistant. In high-pressure suburban corridors — especially Zone 6b and 7a around Philadelphia and its ring counties — deer will graze coneflowers repeatedly. If your garden has significant deer traffic, plant coneflowers behind a barrier or combine them with strongly scented, genuinely resistant plants. In lower-pressure rural areas and Zone 5 gardens, deer impact is rarely a problem. The species tolerates clay soil without amendment and handles rocky, poor soil as well. Goldfinches feed on the seed heads through fall and into winter, so resist deadheading — the dry cone stage feeds birds from October through February. ‘Magnus’ and ‘Pow Wow Wild Berry’ are the best-proven cultivars for Pennsylvania’s humid summers. How to extend coneflower bloom through frost.
7. Lavender (Lavandula angustifolia)
Zones 5–8 | Bloom: June–August | Deer: Resistant | Clay: Will not tolerate — amend or raise
Lavender’s volatile terpene oils (linalool, camphor, borneol) make it one of the most deer-avoided plants in Pennsylvania, but the soil requirement is non-negotiable: lavender roots die in consistently wet or compacted clay within one to two growing seasons. In Zone 6 Pittsburgh gardens with heavy Ultisol clay, raise a dedicated lavender bed 8 to 10 inches, fill it with a mix of 60% native soil plus 40% coarse horticultural grit, and ensure the crown sits above the surrounding grade. Zone 5 Pocono gardeners should choose ‘Hidcote’ or ‘Munstead’ — both are reliably hardy to -15°F. Zone 7 Philadelphia gardeners can experiment with Lavandula ×intermedia (‘Grosso’, ‘Phenomenal’) for larger plants with a longer bloom window. Do not deadhead lavender in Pennsylvania — let stems stand through winter as they provide some insulation at the crown. Lavender growing guide for Zone 6.
8. Black-Eyed Susan (Rudbeckia fulgida ‘American Gold Rush’)
Zones 4–9 | Bloom: July–October | Deer: Resistant in most areas | Clay: Tolerates
Penn State Extension’s flower trial program designated ‘American Gold Rush’ as Exceptional — the highest rating awarded. The key technical detail for Pennsylvania: choose Rudbeckia fulgida, not R. hirta. R. hirta is biennial and dies after its second season; R. fulgida is a true perennial that spreads by rhizomes and builds into larger clumps year after year. ‘American Gold Rush’ specifically outperforms ‘Goldsturm’ in Pennsylvania’s humid summers because it is the only Rudbeckia cultivar with documented resistance to Septoria leaf spot, the fungal disease that regularly defoliates ‘Goldsturm’ in the state’s wet August conditions. Black-eyed Susans tolerate clay soil without amendment. Zone 5 gardeners can plant this variety with confidence — it’s rated to -30°F. Black-eyed Susan complete growing guide.
9. Bee Balm (Monarda didyma)
Zones 4–9 | Bloom: July–August | Deer: Resistant | Clay: Tolerates moist clay
Bee balm is a Pennsylvania native and one of the few plants that genuinely attracts hummingbirds, bees, and butterflies simultaneously. The aromatic thymol compounds in its leaves make deer avoidance reliable across the state. The major challenge in Pennsylvania’s humid summers is powdery mildew, which can turn plants white by August if air circulation is poor. The solution is cultivar selection: ‘Jacob Cline’ (red) has the strongest documented mildew resistance among tall bee balms and is the cultivar Penn State Extension consistently recommends for Zone 6 gardens. Monarda fistulosa (wild bergamot, lavender flowers) is the mildew-immune alternative — it evolved on drier native prairies and resists the fungal pressure of Pennsylvania summers entirely. Divide every three years in spring; clumps that aren’t divided begin to die out in the center. Flowers for pollinators guide.
10. Butterfly Weed (Asclepias tuberosa)
Zones 3–9 | Bloom: June–August | Deer: Resistant | Clay: Needs well-drained lean soil
Butterfly weed is the only milkweed species that monarch butterfly caterpillars can develop on — there is no substitute in the monarch life cycle. Penn State Extension’s 2019 research designated it Exceptional for Pennsylvania gardens. Its deep taproot drives straight down 18 to 24 inches, which creates two important management points: first, transplanting is not possible after year one, so choose the planting location carefully; second, the plant emerges very late in spring (often not until late May in Zone 6), so mark the location clearly to avoid accidentally digging it out. Butterfly weed requires lean, well-drained soil — it evolved on dry meadows and road banks. Heavy clay amendments are counterproductive; if your soil is clay, plant in a raised spot, on a slope, or in a gritty mix where roots stay drier than the surrounding bed.
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→ View My Garden Calendar11. Daylily (Hemerocallis)
Zones 3–9 | Bloom: June–August | Deer: NOT resistant | Clay: Excellent tolerance
Daylilies are among the most clay-tolerant ornamentals available for Pennsylvania gardens, making them a go-to choice for the Ultisol-heavy soils of central and western PA. The Stella de Oro cultivar offers repeat-bloom through the season (June through September with deadheading); extended bloomers like ‘Happy Returns’ or ‘Purple de Oro’ add color variety. The significant caveat: daylilies are a preferred deer browse in high-pressure areas. Deer will strip buds and foliage repeatedly in Zone 7 suburban Philadelphia gardens. In deer-heavy areas, use them in less visible parts of the garden or accept the need for repellents during the bloom window. More zone 6 plant picks.
4 Late Summer and Fall Flowers (August–October)
12. Garden Phlox (Phlox paniculata ‘Jeana’)
Zones 4–8 | Bloom: Mid-July–early September | Deer: Moderate | Clay: Tolerates
Penn State Extension awarded Garden Phlox ‘Jeana’ its Exceptional designation in 2024 — the most recent cohort — specifically for its mildew-free foliage in Pennsylvania’s humid summers. This is not a minor distinction. Most tall garden phlox cultivars are heavily susceptible to powdery mildew in the mid-Atlantic, and afflicted plants become unsightly by August. ‘Jeana’ produces masses of small, fragrant, pale lavender-pink flowers and maintains clean foliage through the hottest, most humid Pennsylvania summers. Space plants 18 to 24 inches apart to ensure airflow — mildew is a water-vapor disease, and crowded plants defeat even resistant cultivars. For white flowers, ‘David’ is the other consistently mildew-resistant selection for PA gardens. Fall-blooming perennials for every zone.
13. New England Aster (Symphyotrichum novae-angliae)
Zones 4–8 | Bloom: August–frost | Deer: Moderate | Clay: Tolerates moist clay
New England aster is one of Pennsylvania’s most ecologically significant fall flowers: it serves as a critical fueling stop for monarch butterflies migrating south through the state’s September and October corridor. Penn State Extension’s native plant program identifies asters as essential for the late-season pollinator community when most other nectar sources have finished. ‘Purple Dome’ (18 to 24 inches) is the compact cultivar that avoids the flop-and-stake problem of full-size New England asters, which can reach 5 to 6 feet and require staking in Zone 6 gardens. For height control without staking on full-size types, cut stems by half in late June and by one-third again in mid-July — this delays and reduces final height without sacrificing fall bloom. Tolerates moist clay soils well.
14. Goldenrod (Solidago)
Zones 3–9 | Bloom: August–October | Deer: Resistant | Clay: Excellent tolerance
Goldenrod is simultaneously Pennsylvania’s most unfairly maligned and most ecologically valuable fall flower. It does not cause hay fever — that’s ragweed, which blooms at the same time but spreads its pollen by wind. Goldenrod pollen is sticky and heavy, moved exclusively by insects. Penn State Extension’s fall native perennial research confirms goldenrod as both deer-resistant and drought-tolerant once established, making it one of the easiest perennials in the state to grow on clay soils. ‘Fireworks’ (3 to 4 feet, arching stems) and ‘Little Lemon’ (18 inches, compact) are the best garden cultivars for keeping goldenrod contained in mixed borders. More than 100 bee species visit goldenrod blooms in Pennsylvania, according to Penn State’s pollinator research.
15. Sedum ‘Autumn Joy’ (Hylotelephium)
Zones 3–9 | Bloom: August–October | Deer: Resistant | Clay: With amendment
Sedum ‘Autumn Joy’ earns its place as a reliable four-season plant in Pennsylvania. It emerges as a compact rosette in April, develops into a mounded plant through summer, opens its flat-topped flower heads in August (opening green, then turning pink, then russet red through October), and holds those dried heads through winter, feeding birds and giving structure to the winter garden. Deer avoid it reliably. In Pennsylvania’s clay soils, amend the planting hole with coarse grit or perlite — the main risk in clay is crown rot from winter moisture accumulation, not summer wet. Once established in amended soil or on a well-drained slope, it requires essentially no care beyond cutting to the ground in March before new growth emerges.
3 Best Annual Flowers for Pennsylvania
Perennials build the garden’s framework, but annuals fill critical gaps and provide the longest non-stop color through Pennsylvania’s summer heat. Penn State Extension’s Cumberland County Flower Trials, one of the nation’s oldest continuous annual trials, test dozens of cultivars each season under real Pennsylvania summer conditions. The 2025 top performers:
16. Zinnia
Annual | Bloom: June–hard frost | Deer: Resistant | Clay: Tolerates
Zinnias are the most heat-tolerant annual for Pennsylvania’s July and August conditions and among the most deer-resistant bedding plants available. Direct sow after the last frost date for your zone (Philadelphia: April 1–5, Pittsburgh: May 1–10, Poconos: May 15–25) or start transplants four weeks earlier. The Benary’s Giant series (4 to 5 feet, large blooms) and Profusion series (compact, disease-resistant) both perform consistently in PSU trial conditions. Powdery mildew can appear on older foliage in humid PA summers, but new flower production continues regardless — trim off affected lower leaves if aesthetics matter. Zinnias are a monarch butterfly favorite and a major nectar source for Pennsylvania’s migrating monarch population from late August through October.
17. Marigold (Tagetes)
Annual | Bloom: June–frost | Deer: Resistant | Clay: Tolerates
Marigolds are a PSU trial standout: the 2025 Cumberland County Flower Trials recognized ‘Milli Vanilli’ French marigold for its large, semi-double, anemone-style flowers in intense yellow, its compact habit, and exceptional heat tolerance through Pennsylvania’s hottest months. French marigolds (*T. patula*) stay compact (10 to 14 inches) and are better suited to Pennsylvania gardens than tall African marigolds, which can suffer stem breakage in the state’s summer thunderstorms. Direct sow after last frost or transplant; begin blooming within 8 to 10 weeks from seed. The pungent foliage and flowers make marigolds consistently deer-resistant — one of the few annuals where deer avoidance is reliable even in high-pressure Zone 7 suburban areas.
18. Petunia ‘Supertunia Tiara Blue’
Annual | Bloom: June–frost | Deer: Moderate | Clay: Tolerates with drainage
Penn State’s 2025 Flower Trials awarded top honors to the Supertunia Tiara series for performance throughout a full Pennsylvania summer — a category where many petunias fail by midsummer due to heat exhaustion or powdery mildew. ‘Tiara Blue’ is a sterile hybrid that requires no deadheading (no viable seeds form, so the plant continuously pushes new flowers) and spreads to 24 to 48 inches, making it an effective container, hanging basket, or front-of-border plant. The heat tolerance that PSU’s trials confirmed is meaningful in Pennsylvania: Zone 7 Philadelphia gardens can see 10 or more days above 90°F in July and August, conditions that collapse standard petunias. The sterile characteristic also means it won’t spread into native plant areas, which matters in gardens near PA woodlands.
Quick Reference: All 18 Pennsylvania Flowers at a Glance
| Flower | Type | Zones | Bloom | Deer | Clay OK |
|---|---|---|---|---|---|
| Daffodil | Perennial bulb | Z3–8 | March–April | Deer-proof | Yes (if drains) |
| Creeping Phlox | Perennial | Z3–9 | April–May | Low risk | No |
| Hellebore | Perennial | Z4–9 | Feb–April | Resistant | Yes |
| Wild Blue Indigo | Perennial | Z3–10 | May–June | Resistant | Tolerates |
| Peony | Perennial | Z3–8 | April–June | Moderate | With amendment |
| Coneflower | Perennial | Z3–9 | June–Sept | NOT resistant | Yes |
| Lavender | Perennial | Z5–8 | June–Aug | Resistant | No (fatal in wet) |
| Black-Eyed Susan | Perennial | Z4–9 | July–Oct | Resistant | Yes |
| Bee Balm | Perennial | Z4–9 | July–Aug | Resistant | Yes |
| Butterfly Weed | Perennial | Z3–9 | June–Aug | Resistant | No |
| Daylily | Perennial | Z3–9 | June–Aug | NOT resistant | Excellent |
| Garden Phlox ‘Jeana’ | Perennial | Z4–8 | July–Sept | Moderate | Yes |
| New England Aster | Perennial | Z4–8 | Aug–frost | Moderate | Yes |
| Goldenrod | Perennial | Z3–9 | Aug–Oct | Resistant | Excellent |
| Sedum ‘Autumn Joy’ | Perennial | Z3–9 | Aug–Oct | Resistant | With grit |
| Zinnia | Annual | All zones | June–frost | Resistant | Yes |
| Marigold | Annual | All zones | June–frost | Resistant | Yes |
| Petunia ‘Supertunia’ | Annual | All zones | June–frost | Moderate | Yes |
For zone-specific planting calendars, see our guide to when to plant in Pennsylvania.
Frequently Asked Questions
What flowers bloom from spring to fall in Pennsylvania?
A sequence of perennials and annuals can keep Pennsylvania gardens in near-continuous color: daffodils and hellebores from February or March, creeping phlox through April and May, followed by indigo and peonies in late spring. Coneflower, bee balm, black-eyed susan, and lavender cover June through August. Garden phlox, asters, goldenrod, and sedum carry through September and October. Zinnias and marigolds fill any gaps in the annual layer from late spring until hard frost. For more on timing spring color specifically, the spring bloom sequence guide covers bulb-to-perennial succession in depth.
What are the most deer-resistant flowers for Pennsylvania gardens?
The most reliably deer-resistant flowers in Pennsylvania are daffodils (deer-proof due to toxic lycorine), lavender, bee balm, wild blue indigo, goldenrod, sedum, butterfly weed, and marigolds. Be aware that coneflower and daylilies — often listed as deer-resistant — are regularly browsed in Pennsylvania’s high-pressure suburban zones. Penn State Extension is explicit about this. For a full state-wide list, see our deer-resistant flowers guide. No plant is guaranteed deer-proof during severe drought or when deer populations peak.
What perennial flowers grow best in Pennsylvania’s clay soil?
The best clay-tolerant perennial flowers for Pennsylvania are daylilies, goldenrod, coneflower, black-eyed susan, bee balm, and New England aster. Hellebores and turtlehead also tolerate heavy, moist clay. Flowers that will fail or die in wet PA clay include lavender, butterfly weed, creeping phlox, and most ornamental grasses. For any clay garden, the most impactful single improvement is adding 3 to 4 inches of compost tilled 12 inches deep, which raises organic matter from the typical 1 to 2% found in Pennsylvania’s Ultisol soils to a more plant-friendly 4 to 5%.
When should I start planting flowers in Pennsylvania?
Timing depends on your zone. Zone 7 Philadelphia gardeners can plant cool-season annuals (pansies, violas) from late February, set out perennial transplants from March, and sow zinnias and marigolds directly after April 1. Zone 6 Pittsburgh and Central PA gardeners should wait until mid-April for transplants and May 1 to 10 for direct-sown annuals. Zone 5 Pocono gardeners have the tightest window: transplants after May 1, direct-sown annuals after May 15. For native Pennsylvania plants and habitat gardening, keystone native plants for the northeast covers the ecologically most valuable species in depth.
Sources
- Penn State Extension, “Incorporate Pennsylvania Native Perennial Plants into the Garden” — Tier 1
- Penn State Extension, “Exceptional Perennials” — Tier 1 (Rudbeckia ‘American Gold Rush’, Phlox ‘Jeana’, Butterfly Weed trial data)
- Penn State Extension, “Native Perennials for Fall” — Tier 1 (Joe Pye Weed, Goldenrod, Asters)
- Penn State Extension, “The Beloved Peony” — Tier 1 (bloom times, planting depth, zone data)
- Penn State Extension, “Top Annual Plant Picks from the 2025 Cumberland County Flower Trials” — Tier 1 (Supertunia Tiara Blue, Marigold Milli Vanilli, Ageratum Monarch Magic)
