Perennials

Annuals complete their entire life cycle in one growing season—you plant them in spring, they bloom all summer, and they die with the first frost, requiring replanting next year. Perennials, on the other hand, are long-term investments that return year after year, often for decades. In Cincinnati’s Zone 6 climate, perennial roots survive our winters underground and send up new growth each spring. While annuals provide continuous color all season, perennials typically bloom for 2-6 weeks but require far less maintenance once established. The tops of most perennials die back in winter (herbaceous perennials), but some like evergreen hellebores keep their foliage year-round. Cost-wise, perennials are more expensive initially but cost nothing in subsequent years, while annuals are cheaper upfront but must be repurchased annually. Many gardeners combine both: perennials for structure and returning beauty, annuals to fill gaps and provide continuous seasonal color. Our staff at Robben Florist can help you design a garden that balances both for maximum impact with minimal maintenance.

The ideal times to plant perennials in Cincinnati are spring (April through May) and fall (September through October). Spring planting allows plants a full growing season to establish strong root systems before winter, and you’ll typically see some blooms the first year. Fall planting is actually preferred by many experts because warm soil encourages root growth while cool air reduces water needs—roots establish beautifully while tops go dormant for winter. Avoid planting during the heat of summer (July-August) when stress is high and watering demands are intense. Container-grown perennials from Robben Florist can technically be planted anytime the ground isn’t frozen, but spring and fall offer the best conditions for establishment. If you must plant in summer, choose a cool, cloudy day, water deeply and frequently, and provide temporary shade. For bare-root perennials like peonies and daylilies, fall planting (September-October) is strongly preferred as they establish better in cool conditions.

While most perennials prefer amended soil, some actually thrive in Cincinnati’s heavy clay with minimal improvement: Daylilies are nearly indestructible in clay and bloom reliably; Hostas love moisture-retentive clay, especially in shade; Black-eyed Susans (Rudbeckia) tolerate clay beautifully; Purple Coneflowers (Echinacea) establish well in clay; Siberian Iris thrives in heavy, moisture-retentive soil; Joe Pye Weed loves clay and wet conditions; Asters perform well in unamended clay; Bee Balm (Monarda) tolerates clay if not waterlogged; Ornamental Grasses like Miscanthus handle clay excellently; and Sedums need good drainage but tolerate clay if not soggy.

Unlike annuals that bloom continuously, most perennials have a specific bloom period of 2-6 weeks. The secret to season-long color is succession planting—choosing varieties that bloom at different times throughout the growing season. For spring (March-May), plant hellebores, bleeding heart, creeping phlox, and peonies. For early summer (June-July), choose baptisia, salvia, catmint, and daylilies. For mid-summer (July-August), feature coneflowers, black-eyed Susans, bee balm, and rudbeckia. For late summer (August-September), plant helenium, coreopsis, and Russian sage. For fall (September-November), include asters, sedum, and ornamental grasses. Some perennials like catmint, salvia, and coreopsis will rebloom if deadheaded (cut spent flowers), extending their season. Fertilize in early spring and after bloom, water during dry spells, and divide every 3-5 years to maintain vigor.

For Cincinnati’s Zone 6 gardens with minimal upkeep, choose these bulletproof perennials: Daylilies are nearly indestructible, drought-tolerant once established, and bloom reliably with zero care; Hostas thrive in shade, tolerate clay soil, and need only spring cleanup; Sedum ‘Autumn Joy’ requires no deadheading, division, or special care—just blooms beautifully; Black-eyed Susans spread to fill spaces, tolerate heat and drought, and reseed readily; Purple Coneflowers (Echinacea) are drought-tolerant, disease-resistant, and feed birds in winter; Ornamental Grasses like Miscanthus provide year-round interest with zero maintenance; Russian Sage handles heat, drought, and poor soil while blooming for months; Catmint reblooms without deadheading and repels deer; Siberian Iris blooms reliably and divides rarely; and Coral Bells provide colorful foliage year-round with no deadheading needed.

Create a pollinator paradise in your Northern Kentucky garden with these perennials that attract beneficial wildlife: For butterflies, plant Purple Coneflowers (Echinacea)—a monarch favorite; Black-eyed Susans attract numerous butterfly species; Butterfly Weed (Asclepias) is essential for monarchs; Asters provide critical late-season nectar; Joe Pye Weed attracts swallowtails and more; and Milkweed is the only host plant for monarch caterpillars. For bees, choose Catmint (Nepeta) which bees adore; Salvia provides nectar all summer; Bee Balm (Monarda) is aptly named; Russian Sage attracts native bees; and Coreopsis feeds many bee species. For hummingbirds, plant Cardinal Flower (Lobelia cardinalis)—hummingbirds love red tubular flowers; Bee Balm attracts both bees and hummingbirds; Salvia, especially red varieties; Coral Bells (Heuchera) with delicate blooms; and Columbine provides early-season nectar.