11 late summer perennials that peak when the garden is running out of steam

The most impactful late-summer perennials are rudbeckia (long bloom, native, drought-tolerant), Joe Pye weed (tall, structural, pollinator magnet), coneflower (extends from summer into fall), and garden phlox (longest bloom period of any summer perennial). These four alone will c

By late July, most spring-planted borders are spent. The peonies are green mounds, the iris foliage is browning, and the early daylilies have finished. Late summer — August through September — is the trough most perennial gardens fall into, and it's the gap that's easiest to fill with the right plant choices.

This list covers 11 perennials that bloom from late July through September. All are reliably hardy in zones 4—8, and most are native to eastern North America, which means they're well-adapted to the heat, humidity, and late-summer drought that characterize that period.

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1. Black-eyed Susan (Rudbeckia fulgida 'Goldsturm')

Zones 3—9. Blooms late June through October — but peak bloom is August and September. Golden yellow flowers with dark centers, 24—30 inches tall. Full sun; drought-tolerant once established.

I grow 'Goldsturm' in three border locations on my Long Island property. Per Penn State Extension, Rudbeckia fulgida 'Goldsturm' is the standard cultivar for long bloom, disease resistance, and compact habit. The species R. fulgida is native to central and eastern North America and requires no deadheading — spent flowers persist as ornamental seedheads that birds use in winter. It spreads slowly by rhizomes and can be divided every 3—4 years to keep clumps tight.

2. Joe Pye weed (Eutrochium purpureum)

Zones 3—9. Blooms August through September; large mauve-pink flower domes on architectural stems 5—7 feet tall. Full sun to partial shade; tolerates moist soil.

Per NC State Extension, Eutrochium purpureum is native to eastern North America and is one of the most important late-season nectar sources for large pollinators — monarch butterflies, swallowtails, and bumblebees work the flowers heavily. At 6—7 feet, it needs staking only in shade; in full sun it stands without support. 'Gateway' is a compact cultivar at 4—5 feet. Cut to 6 inches in early spring; the hollow stems provide overwintering habitat for native bees.

3. Garden phlox (Phlox paniculata)

Zones 3—8. Blooms July through September — with the right cultivar, bloom extends 10—12 weeks, making it the longest-blooming perennial for the late summer border. Large fragrant flower heads, 24—48 inches tall. Full sun.

Per Missouri Botanical Garden, Phlox paniculata is native to the eastern US and one of the most fragrant summer perennials available. The primary management challenge is powdery mildew — particularly on older cultivars. Mildew-resistant selections include 'David' (white, excellent mildew resistance), 'Delta Snow' (white), 'Jeana' (small lavender flowers, outstanding mildew resistance, sterile so it won't self-seed). Space 18—24 inches apart for air circulation. Deadhead to extend bloom.

4. Coneflower (Echinacea purpurea)

Zones 3—9. Blooms July through September; rosy-purple petals with prominent orange-brown central cone, 2—4 feet tall. Full sun; drought-tolerant.

I grow coneflower in my main perennial border. Per Penn State Extension, the native species (E. purpurea) is more reliably perennial than most of the double-flowered and novelty cultivars, which tend to be shorter-lived. The central seed cone persists through fall and winter and is heavily used by finches. Divide every 4—5 years when the center opens. In Sandy Long Island soil it performs well with minimal amendments — it's native to calcareous prairie soils and tolerates low fertility.

5. Russian sage (Perovskia atriplicifolia)

Zones 4—9. Blooms July through October; hazy blue-purple flower spikes on silvery-gray aromatic stems, 3—5 feet tall. Full sun; outstanding drought tolerance.

Per Penn State Extension, Perovskia is technically a woody subshrub that performs as an herbaceous perennial in zones 4—7, dying back to the crown each winter. It is one of the most drought-tolerant ornamental plants for the Northeast — thriving in the kind of hot, dry, reflected-heat conditions that kill most perennials. The silvery stems provide visual interest from first emergence through frost. Do not cut back in fall; the stems insulate the crown. Cut to 6—8 inches in early spring.

6. Catmint 'Walker's Low' (Nepeta × faassenii 'Walker's Low')

Zones 3—8. Blooms May—July (primary) and September—October (rebloom after cutback). Lavender-blue flower spikes, 18—24 inches. Full sun; drought-tolerant; deer-resistant.

I cut back my catmint clumps to 4—6 inch mounds in early August, and by mid-September they've produced a substantial second flush of bloom. Per Missouri Botanical Garden, 'Walker's Low' earned the Perennial Plant Association's Plant of the Year in 2007 based on overall performance, rebloom, and low maintenance. Bees visit it heavily both in the primary bloom and rebloom periods. Self-seeds modestly.

7. Agastache (Agastache species and hybrids)

Zones 5—9 (varies by species). Blooms July through frost; tubular flowers in orange, yellow, lavender, or pink on upright stems 2—4 feet tall. Full sun; excellent drought tolerance; deer-resistant.

Per NC State Extension, Agastache species are native to North America and exceptional for late-season hummingbird and butterfly visits. The anise-scented foliage is deer-resistant. 'Blue Fortune' (A. × hybrida) is cold-hardy to zone 4 and the most widely available selection; 'Golden Jubilee' has yellow foliage with lavender flowers; 'Black Adder' (zone 5) has dark purple stems with dense blue-violet flower spikes. Agastache dislikes wet winter soil — excellent drainage is more important than cold hardiness.

8. Tall garden phlox (Phlox paniculata × 'Peacock' and related tall forms)

As above, but several newer introductions bloom specifically in late August through October. 'Peacock White', 'Peacock Bright Eyes', and the 'Flame' series are compact (18—24 inches) with improved mildew resistance and later bloom timing than older varieties.

9. Swamp milkweed (Asclepias incarnata)

Zones 3—6 (hardy), performing well through zone 9 in summer. Blooms July through August; clusters of small pink-mauve flowers on branched stems, 3—4 feet tall. Full sun; tolerates moist and wet soil; important monarch host plant.

Per Penn State Extension, Asclepias incarnata is a native milkweed that tolerates wet soils where most perennials fail. Unlike common milkweed (A. syriaca), it does not spread aggressively and is better suited to garden borders. It is a host plant for monarch butterflies and provides nectar for many native bees and fritillaries. It emerges late in spring (mid-May in zone 7) — don't assume it has died. Seed pods are ornamental in fall.

10. Goldenrod (Solidago species)

Zones 3—9. Blooms August through October; bright yellow plumes, 2—5 feet tall. Full sun; drought-tolerant; native to North America.

Per Penn State Extension, goldenrod is not an allergy plant — that's ragweed, which blooms simultaneously but has wind-dispersed pollen. Solidago pollen is insect-dispersed and too heavy for inhalation. Native goldenrods are among the top 3 plants for native bee species diversity, per Xerces Society research. 'Fireworks' (Solidago rugosa) has graceful arching flower branches; 'Little Lemon' (Solidago × hybrid) stays under 18 inches. Allow to stand through winter for bird food.

11. Hyssop (Hyssopus officinalis)

Zones 3—9. Blooms July through September; dark blue-violet flower spikes on semi-woody stems 18—24 inches tall. Full sun; drought-tolerant; deer-resistant; aromatic foliage.

Per Missouri Botanical Garden, hyssop is an underused late-summer perennial — it provides reliable blue color during the August period when little else in the blue-purple range is blooming. It's semi-woody and should not be cut back hard in fall; trim lightly after bloom. Bees, especially bumblebees, visit heavily. The aromatic foliage deters deer. Short-lived (3—5 years) but self-seeds.

Designing for late summer bloom

The most effective late summer borders combine vertical elements (Joe Pye weed, tall garden phlox) with mid-height masses (rudbeckia, coneflower, agastache) and edging plants with long bloom periods (catmint rebloom, black-eyed Susan). Per Missouri Botanical Garden, ornamental grasses (Panicum virgatum, Miscanthus) provide structural backdrop that makes flowering perennials read more dramatically.

Color palette: late summer naturally produces gold, yellow, orange, and purple. Lean into this rather than fighting it. White-flowered selections ('David' phlox, 'White Swan' coneflower) punctuate without disrupting the overall warm palette.

Timing is the other design consideration. In zone 7, late July through late August is the hardest window — temperatures are highest, rainfall often drops, and plants that aren't adapted to heat and drought show it. The native plants on this list (rudbeckia, coneflower, Joe Pye weed, goldenrod, swamp milkweed) are heat-adapted for this reason. Pair them with agastache and Russian sage, which are built for drought, and you have a late summer border that doesn't require supplemental watering in most years.

Per Clemson HGIC, established perennials in average soil need supplemental water only when rainfall drops below 1 inch per week for more than 3 consecutive weeks. Native prairie plants like rudbeckia and coneflower can extend this to 4—5 weeks before showing stress. Newly planted perennials need more frequent irrigation during their first season regardless of species.

Frequently asked

How do I extend late summer bloom into fall?

Deadheading extends bloom on phlox and agastache by 2—4 weeks, per Penn State Extension. For rudbeckia and coneflower, deadheading has minimal effect — they bloom until frost regardless. The natural transition to fall color in ornamental grasses and the late-season asters picks up where late summer perennials leave off without any intervention.

What are the deer problems with late summer perennials?

High deer pressure is my situation on Long Island. Per my experience, rudbeckia and coneflower are lightly to moderately browsed; Joe Pye weed is generally avoided; garden phlox is heavily browsed; Russian sage is avoided (aromatic); catmint is avoided (aromatic); swamp milkweed is avoided (milky sap is bitter). Wire protection or Plantskydd deer repellent spray on the phlox in summer is the practical solution.

Can late summer perennials handle shade?

Most listed here need full sun (6+ hours). Exceptions: Joe Pye weed tolerates partial shade; garden phlox tolerates morning-only sun but mildews worse. For shaded late summer borders, Actaea (cimicifuga) and toad lily (Tricyrtis) are the reliable choices, but they're not in this list because they're cooler-weather bloomers transitioning into fall rather than true late summer.

Sources

1. Penn State Extension — Rudbeckia Black-eyed Susans
2. Penn State Extension — Echinacea Coneflowers
3. Penn State Extension — Russian Sage
4. Penn State Extension — Swamp Milkweed
5. Missouri Botanical Garden — Plant Finder
6. NC State Extension — Eutrochium purpureum
7. NC State Extension — Agastache
8. Xerces Society — Goldenrod for Pollinators