Zone 5 to 7 Perennials for Pennsylvania: 12 Plants Proven to Survive -20°F Winters and Still Bloom June to October
12 perennials zone-matched for Pennsylvania’s Zone 5 to 7 climate — with deer-resistance ratings, clay-soil notes, and Penn State Extension-backed cultivar picks for every region.
Pennsylvania gives perennials exactly what they need to return every year: hot summers to build root reserves and cold winters to trigger dormancy. The problem is that the same climate that makes perennials possible also makes plant selection unforgiving. Choose the wrong species for your county’s zone, and you’ll be replanting in May. Choose the right one, and you’ll be dividing it in ten years to give away to your neighbors.
This guide covers 12 perennials matched specifically to Pennsylvania’s Zone 5a through 7a range, with honest notes on deer resistance, clay tolerance, and the disease issues that humid PA summers create. Every plant here is confirmed by Penn State Extension or NC State Extension — not sourced from generic “best of” lists.
Why Pennsylvania Is Perfect — and Tricky — for Perennials
The mechanism behind why perennials return is worth understanding before you spend money at the nursery. In late summer, perennials shift energy from above-ground growth to below-ground carbohydrate storage in roots, rhizomes, or woody crowns. As days shorten and soil temperatures drop below 50°F, temperature-sensing genes brake further growth and harden cell membranes against ice crystal formation. In spring, warming soils and lengthening days reverse the process. A plant “rated for Zone 5” has been tested and confirmed to survive winter minimum temperatures of −15 to −10°F through this mechanism — which means every plant on this list is guaranteed to return in the Poconos, Pittsburgh, and Philadelphia alike.
Pennsylvania’s specific challenges go beyond zone ratings, though. The Piedmont and Ridge-and-Valley regions have heavy clay soils that pool water in winter and suffocate roots. Summer humidity — especially in Pittsburgh’s Ohio Valley and the southeastern lowlands — drives powdery mildew on susceptible species. And with roughly 1.5 million white-tailed deer in the state, browsing pressure here is among the highest in the country. The plants below were selected with all three of these realities in mind.
The 12 Best Perennials for Pennsylvania at a Glance
All 12 are rated Zone 5 or hardier — suitable for every Pennsylvania county from Erie to Philadelphia.
| Plant | Zones | Height | Bloom | Sun | Deer | Best For |
|---|---|---|---|---|---|---|
| Creeping Phlox | 3–9 | 6 in | Apr–May | Full sun | ✓ High | Slopes, edges, spring color |
| Wild Blue Indigo | 3–10 | 3–5 ft | May–Jun | Sun–pt shade | ✓ High | Structural anchor, back of border |
| Purple Coneflower | 3–9 | 24–36 in | Jun–Sept | Full sun | Low | Pollinators, clay soil |
| Butterfly Weed | 3–9 | 1–3 ft | Jun–Aug | Full sun | ✓ Moderate | Monarchs, dry/poor soil |
| Foxglove Beardtongue | 3–8 | 2–5 ft | Jun–Jul | Sun–pt shade | ✓ High | Humid sites, hummingbirds |
| Bee Balm | 4–9 | 2–4 ft | Jul–Aug | Full sun | Moderate | Hummingbirds, moist borders |
| Black-Eyed Susan | 4–9 | 22–27 in | Jul–Oct | Full sun | Moderate | Long bloom, clay soil |
| Garden Phlox | 4–8 | Up to 5 ft | Jul–Sept | Full sun–pt shade | Variable | Fragrant, cottage borders |
| Dense Blazing Star | 5–10 | 2–5 ft | Jul–Sept | Full sun | ✓ High | Vertical accent, monarchs |
| Astilbe | 3–9 | 18–48 in | Jun–Aug | Part shade | ✓ High | Shaded borders, moist spots |
| Sedum ‘Autumn Joy’ | 3–9 | 18–24 in | Aug–Oct | Full sun | Moderate | Dry gardens, 4-season interest |
| New England Aster | 4–8 | 2–6 ft | Aug–frost | Full sun | Moderate | Fall color, monarch migration |
Spring Bloomers: Color Before Summer Arrives
1. Creeping Phlox (Phlox subulata) — Zones 3–9
Creeping phlox opens in April and carpets the ground with solid sheets of pink, lavender, white, or magenta before most PA gardens have woken up. At just 6 inches tall, it spreads 2 to 3 feet through low, mat-forming stems, making it ideal for slopes, rock gardens, and front-of-border edges where it spills over stones cleanly.
Penn State Extension confirms it tolerates poor, dry soil and requires minimal care after establishment. In terms of deer resistance, it’s one of the strongest options in this list: only about 12 percent of surveyed gardens reported deer damage to P. subulata, and nearly all cases occurred during prolonged winter thaws when alternative forage was buried under snow. The needle-like, semi-evergreen foliage is simply unpalatable to deer under normal conditions. Named cultivars worth seeking: ‘Emerald Blue’ (lavender) and ‘Amazing Grace’ (white with lilac eye). After bloom, shear lightly with scissors to maintain compact form and encourage fresh growth.
2. Wild Blue Indigo (Baptisia australis) — Zones 3–10
Wild blue indigo earns its place in every PA garden for one reason most guides overlook: it is a nitrogen-fixing legume. Root-associated bacteria convert atmospheric nitrogen into plant-available form, gradually improving PA’s often acidic, nutrient-poor soils — a free soil amendment that builds year after year. Penn State Extension calls it “easy to grow” with “no chemical input needed” and “virtually trouble-free” after establishment.
Patience is the only ask. The deep taproot that makes transplanting nearly impossible also means the plant takes two to three years from a nursery transplant before producing its full display — a 3 to 5-foot shrub-like mound studded with 6 to 9-inch indigo-blue flower spikes in late May and June. By year four, a single plant commands attention from 10 feet away. It is also host to six butterfly species and is strongly deer-resistant. PA native plants that support local wildlife rarely deliver this much ecological value from one specimen.
Early Summer Bloomers: June and July
3. Purple Coneflower (Echinacea purpurea) — Zones 3–9
Pennsylvania’s state insect, the firefly, and its most photographed garden bird, the American goldfinch, both have a relationship with purple coneflower. Goldfinches wait for the seed heads to ripen in late summer and early fall, clinging to the spiky cones while extracting seeds. If you want goldfinches in your garden, leave the spent flower heads standing — cut them in late February instead.
Penn State Extension confirms coneflower grows in both clay and rocky soils and is drought-tolerant once established, thanks to deep, thick roots. It blooms late June through early September — a solid 10 to 12 weeks. Be honest about deer resistance, though: PSU specifically notes that coneflower is not deer-resistant; buds and new leaves are vulnerable to browsing. In high-deer-pressure areas, protect new plants through their first summer. The cultivar ‘Magnus’ produces larger, flatter flowers than the species; for more color options, ‘Pow Wow Wild Berry’ offers deep rose-purple. Explore our full coneflower growing guide for dividing and overwintering tips.
4. Butterfly Weed (Asclepias tuberosa) — Zones 3–9
Butterfly weed makes this list not because it has the showiest flowers — though the clustered orange blooms from June through August are striking — but because monarch caterpillars cannot survive without it. Milkweed is the sole larval host plant for monarchs, and eastern populations have declined sharply as milkweed disappeared from farmland across PA and the mid-Atlantic. A single clump in your garden breaks that decline at the local level.
Penn State’s 2017 Exceptional Perennial award went to A. tuberosa with good reason. Its deep taproot makes it more drought-tolerant than most milkweeds and actually suits PA’s often thin, poor soils better than amended beds. Two things to know for PA gardeners: first, it emerges very late in spring — mark the location in fall, because bare soil in April does not mean the plant died. Second, it is generally deer-resistant compared to other milkweeds, though this varies by local deer pressure. Do not heavily mulch over the crown in winter.
5. Foxglove Beardtongue (Penstemon digitalis) — Zones 3–8
Most western penstemons struggle in PA’s humid summers and heavy soils, but foxglove beardtongue is native to the eastern woodlands and actually evolved for exactly these conditions. Penn State’s native plant list confirms it for moist to dry soils in full sun to partial shade — covering a wider range of PA garden situations than almost any perennial on this list.
It blooms in June and July with tall spikes of tubular white flowers that attract hummingbirds and native bumblebees. At 2 to 5 feet, it fills the mid-border gap before coneflowers and black-eyed Susans take over in July. Deer rarely browse it. The cultivar ‘Husker Red’ adds deep burgundy foliage that holds color from emergence in April through bloom, giving the plant a second season of interest beyond the flowers. Divide every three to four years in early spring to maintain vigor.
Mid-Summer Bloomers: July to September
6. Bee Balm (Monarda didyma) — Zones 4–9
Bee balm is the peak-summer hummingbird magnet in PA gardens, with tubular red, pink, or lavender flowers that hummingbirds prefer over nearly any other perennial from July through August. The challenge in Pennsylvania is humidity: older bee balm cultivars develop heavy powdery mildew by mid-August, turning from a garden feature into an eyesore.
Cultivar selection solves this problem. ‘Jacob Cline’ (M. didyma) produces deep red flowers on 3 to 5-foot stems and is widely considered the best mildew-resistant red bee balm available. ‘Raspberry Wine’ offers wine-red blooms with good resistance at 3 to 4 feet. If you want mildew immunity rather than just resistance, choose Monarda fistulosa (wild bergamot, lavender flowers) — a PA native that evolved in drier, more open conditions and simply does not attract mildew the way M. didyma does. Regardless of cultivar, space plants 18 to 24 inches apart and divide every three years as the center dies out, which is a natural bee balm cycle, not a failure.
7. Black-Eyed Susan (Rudbeckia fulgida ‘American Gold Rush’) — Zones 4–9
Penn State named ‘American Gold Rush’ its 2023 Exceptional Perennial, and the reason matters for PA gardeners specifically: it is resistant to septoria leaf spot, a fungal disease that turns the foliage of the popular ‘Goldsturm’ cultivar yellow and patchy by August in humid PA summers. ‘American Gold Rush’ stays clean through October.
The species note is also important: Rudbeckia fulgida is the true perennial black-eyed Susan (returning reliably for many years via rhizomes). R. hirta, sold everywhere as a “perennial,” is technically biennial and may not return after year two. If you’re buying in spring, check the label for ‘fulgida’ specifically. At 22 to 27 inches with blooms from July through October — the longest bloom window of any plant in this guide — it is the reliable workhorse of the PA summer border. Zone 6 black-eyed Susan care guide covers dividing, feeding, and fall management.
8. Garden Phlox (Phlox paniculata ‘Jeana’) — Zones 4–8
Penn State designated ‘Jeana’ as its 2024 Exceptional Perennial, specifically because its foliage does not develop powdery mildew — the defining failure of older garden phlox cultivars in PA’s humid summers. Older varieties like ‘Bright Eyes’ are typically white with fungal powder by mid-August. ‘Jeana’ stays clean through September, when it closes its bloom with dense pink flower heads up to 6 inches across that pollinators swarm.
Plant in full sun to light shade, space at 18 to 24 inches for airflow, and deadhead spent clusters to encourage continuous bloom. At up to 5 feet in full flower, ‘Jeana’ needs a spot at the mid-to-back border where it won’t shade smaller plants. If you want earlier white blooms, pair it with ‘David’ (another mildew-resistant cultivar, white flowers, July through August) for a two-month white-to-pink succession from a single genus. Deer pressure on phlox is variable — creeping phlox is reliably ignored, but garden phlox is occasionally browsed. In high-deer areas, use a protective spray on new foliage in May and June.
Late Summer and Fall Bloomers: August to Frost
9. Dense Blazing Star (Liatris spicata) — Zones 5–10
Dense blazing star has one feature no other plant on this list shares: its flowers open from the top of the spike downward, not from the bottom up as virtually all other flower spikes do. This reversed bloom direction means the display begins with a tight purple crown at the top and descends over six to eight weeks through July and September — a visual effect that rewards attention.
Penn State’s trial garden has grown L. spicata directly and confirms it thrives in Pennsylvania with only minor, cosmetic powdery mildew during the hottest and most humid periods. At Zone 5 hardiness, it covers every PA county including the Poconos. It prefers slightly acidic soil (pH below 6.8), which most of PA’s naturally acidic woodland and farm soils already provide. Plant in full sun with moderate moisture; established clumps tolerate drought. Monarch butterflies use the flowers as a major late-summer nectar source before their southward migration, and songbirds eat the seeds in fall. Often survives 20 years or more without division.
10. Astilbe (Astilbe × arendsii) — Zones 3–9
Astilbe is the one shade specialist in this guide — and for the significant portion of PA gardens under tree canopy or against north-facing walls, it is irreplaceable. NC State Extension confirms it is resistant to deer and rabbits, with no serious insect or disease problems. The feathery plumes in red, pink, peach, purple, and white rise above fern-like bronze or dark green foliage from June through August depending on variety.
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→ View My Garden CalendarThe critical requirement is soil moisture. Astilbe will not tolerate drought — dry soil causes the foliage to brown at the edges and flower production to collapse. This is not a weakness in PA’s context: the shaded, moist spots under trees and along north walls that most perennials reject are precisely where astilbe thrives. To extend the display across the full season, stagger three varieties by bloom time: early-season ‘Deutschland’ (white, June), mid-season ‘Fanal’ (deep red, July), and late ‘Visions in Pink’ (August). Divide every four years in spring when the center becomes woody and flower production declines. Full astilbe care guide for Zone 6 covers soil preparation for PA’s clay-heavy ground.
11. Sedum ‘Autumn Joy’ (Hylotelephium ‘Herbstfreude’) — Zones 3–9
No perennial in this guide delivers more across the calendar year than ‘Autumn Joy’. It emerges in April with thick, succulent gray-green rosettes that look architectural even before bloom. Flower buds form by July — flat-topped clusters the color of pale jade. By late August those clusters open pale pink, deepening to salmon and copper through September. By October they rust to a rich bronze-brown that holds through winter snow as a skeletal garden feature. That’s four distinct visual phases from a single plant.
It is one of the most drought-tolerant perennials available, and once established requires almost no supplemental water in a typical PA growing season. The one weakness is clay: wet, waterlogged soil in winter leads to crown rot. If your PA garden has heavy clay, amend the planting area with grit or perlite to improve drainage before planting, or raise the crown 1 to 2 inches above grade. In well-drained soil it is virtually indestructible, self-supporting, and fully hardy through Zone 3. Deer occasionally browse it when food is scarce but typically pass it over.
12. New England Aster (Symphyotrichum novae-angliae) — Zones 4–8
New England aster closes the season in a way nothing else does. It holds back all summer while other perennials perform, then explodes in violet-purple from August through hard frost — often blooming into November in Philadelphia’s Zone 7a. Penn State’s native perennial guide includes it as one of the most ecologically valuable fall perennials in the region. The timing is deliberate: its nectar production peaks during monarch butterfly migration, providing the last major fuel stop before monarchs cross into New Jersey and head toward the Delaware Valley on their way to Mexico.
The straight species can reach 6 feet and may flop without staking. Cut it back by half in late June and again by a third in mid-July — this reduces height to a manageable 2 to 3 feet without sacrificing any bloom. The compact cultivar ‘Purple Dome’ reaches just 18 to 24 inches and requires no cutting back. Leave seed heads standing through winter for goldfinches. PA’s best fall-blooming perennials pairs well with this entry if you want to extend the season further.
Zone by Zone: Matching Plants to Your PA Region
Pennsylvania spans more than 400 miles east to west and includes elevations from sea level to 3,213 feet at Mount Davis in Somerset County. That range translates to meaningfully different growing conditions across three main zones.
Poconos and Northern Tier (Zone 5a–5b): Bradford, McKean, Potter, Sullivan, and Susquehanna counties experience minimum temperatures of −20 to −10°F. The growing season averages 140 to 155 frost-free days. All 12 plants in this guide are rated Zone 5 or colder: 7 of the 12 are rated Zone 3, making them fully bullet-proof for even the harshest northern PA winter. The primary risk in Zone 5 is not cold but drainage — freeze-thaw cycles in clay soil heave shallow roots. Plant high (crown at or just above grade) and mulch lightly with shredded leaves after the ground freezes.
Pittsburgh and Central PA (Zone 6a–6b): Pittsburgh, Harrisburg, and Allentown sit in the sweet spot where all 12 plants perform at their best. The Ohio Valley humidity around Pittsburgh creates the heaviest mildew pressure in the state — prioritize Penn State’s mildew-resistant picks: Phlox ‘Jeana’, Rudbeckia ‘American Gold Rush’, Monarda ‘Jacob Cline’, and Liatris (which showed only minor mildew in Penn State’s own trial garden). In the Zone 6 plant guide, you’ll find additional companions that extend bloom beyond this core list.
Philadelphia and Delaware Valley (Zone 7a): The mildest region, with minimum temperatures of 0 to 5°F and roughly 200 frost-free days. All 12 plants are within range; many will bloom earlier and longer than their Zone 5 equivalents. For a deeper look at Pennsylvania’s full regional gardening conditions including soil types and frost date maps, see our state gardening overview. The opportunity here is the fall season: add Aromatic Aster (Symphyotrichum oblongifolium) to extend bloom into November — it is PA-native and hardy to Zone 4.
Pennsylvania Perennial Care Calendar
| Month | Key Tasks |
|---|---|
| March | Remove winter mulch as temps stabilize above freezing. Cut back dead stalks from Sedum, Liatris, and Aster. Mark butterfly weed locations — it does not emerge until late May. |
| April | Creeping phlox blooms. Divide Bee Balm, Aster, and Rudbeckia if clumps have died out in the center. Plant container perennials after last frost (Zone 5: mid-May; Zone 6: mid-April; Zone 7: early April). |
| May | Wild Blue Indigo blooms. Cut New England Aster by half to control height. Apply 2 inches of mulch around crowns, keeping material away from stems. |
| June | Coneflower, Butterfly Weed, Penstemon, and Astilbe begin blooming. Cut Aster by one-third again in mid-June for final height control. Water newly planted perennials deeply once or twice weekly until established (6–8 weeks). |
| July | Peak season: Bee Balm, Rudbeckia, Phlox, Liatris. Deadhead Garden Phlox for extended bloom. Remove faded Bee Balm flower heads to discourage mildew spread. |
| August | Sedum ‘Autumn Joy’ opens. New England Aster begins. Stop fertilizing all perennials after August 1 — late nitrogen pushes soft growth that does not harden before frost. |
| September | Aster peak. Monarchs migrating — leave Liatris seed heads and Aster blooms intact. Sedum deepens to copper-rust. Good time to plant or transplant perennials (roots establish over winter). |
| October–November | Leave seed heads standing for birds (goldfinches on Coneflower and Liatris). Lightly mulch crowns of Bee Balm and Phlox in Zone 5 after ground freezes. |
| December–February | Sedum and Liatris provide winter structure under snow. No action needed. Avoid working frozen soil near crowns. |
Frequently Asked Questions
Will all 12 plants survive a Zone 5 Pennsylvania winter?
Yes. Every plant on this list is rated Zone 5 or harder. Liatris is the most tender at Zone 5 — it is confirmed by Penn State Extension for zones 5 through 10. The remaining 11 are rated Zone 3 or Zone 4, meaning they survive minimum temperatures well below what even the Pocono Mountains typically deliver.
Which plants are most deer-resistant for high-pressure PA areas?
The strongest choices are Wild Blue Indigo (deer-resistant per Penn State), Creeping Phlox (only 12% damage rate), Foxglove Beardtongue (deer-resistant), Dense Blazing Star (deer-resistant), and Astilbe (resistant to deer and rabbits per NC State Extension). Butterfly Weed and Coneflower are moderate. For a full PA deer-resistance strategy, see deer-resistant flowers for every season.
My soil is heavy clay. Which plants handle it best?
Purple Coneflower, Liatris spicata, Butterfly Weed (taprooted — breaks through clay), Penstemon digitalis, and New England Aster all tolerate heavy clay. Sedum ‘Autumn Joy’ and Garden Phlox are clay-intolerant; amend the planting hole with grit or perlite before planting either. Astilbe actually thrives in moist, clay-influenced soils as long as they do not pool standing water.
When should I plant perennials in Pennsylvania?
Spring (after last frost) and fall (August through October) are both ideal. Fall planting is slightly better for root establishment — plants put down roots through October before going dormant, then break dormancy in spring with an established root system already in place. Avoid planting in summer heat above 85°F.
Do I need to mulch PA perennials for winter?
A light layer of shredded leaves after the ground freezes (typically December) helps in Zone 5 and insulates against freeze-thaw heaving. Do not mulch before the ground freezes — warm mulch attracts rodents that nest against crowns. In Zone 6 and 7, mulching is optional for all 12 plants listed here.
Sources
- Penn State Extension. “Incorporate Pennsylvania Native Perennial Plants into the Garden.” extension.psu.edu
- Penn State Extension. “Exceptional Perennials.” extension.psu.edu
- Penn State Extension. “Native Perennials for Fall.” extension.psu.edu
- Penn State Extension. “Phlox in the Home Garden.” extension.psu.edu
- Penn State Extension. “Purple Coneflower.” extension.psu.edu
- Penn State Extension. “False Blue Indigo.” extension.psu.edu
- Penn State Extension. “Dense Blazing Star.” extension.psu.edu
- NC State Extension Gardener Plant Toolbox. “Astilbe x arendsii.” plants.ces.ncsu.edu
