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Hardy Plant Guide

Blue Oat Grass (Helictotrichon sempervirens)
This distinctive cool-season grass forms fountain-like mounds of intense blue-gray foliage 12-18" tall. Arching tan flower stems rise to 30" in early summer but are secondary to the excellent foliage color. Extremely hardy to Zone 4 and semi-evergreen in mild winters, it requires excellent drainage and full sun to maintain its blue color. Individual plants live 3-5 years in Zone 4 and rarely need division. Use as specimens, in rock gardens, or as a color contrast with dark green or burgundy foliage plants.

Coreopsis (Tickseed)
These low-maintenance perennials deliver masses of daisy-like flowers throughout summer. Thread-leaf varieties (C. verticillata) are the most reliable in Zone 4, with finely textured foliage and yellow blooms on 15-24" stems. 'Moonbeam' (pale yellow) and 'Zagreb' (golden yellow) are exceptional performers. They thrive in full sun with well-drained soil and benefit from a mid-summer trim to refresh blooms. Drought tolerant once established and rarely bothered by pests.

Delphinium
These stately perennials produce magnificent spires of blue, purple, pink, or white flowers in early to midsummer. The Pacific Giant hybrids reach 4-6' tall, while the Belladonna types grow 3-4' with a more open habit. All require rich, well-drained soil, protection from strong winds, and prefer cool summer climates. They're reliably hardy to Zone 3 but often short-lived in challenging conditions. Stake tall varieties and cut back after flowering for possible fall rebloom.

Echinacea (Purple Coneflower)
A prairie native with outstanding durability, Echinacea produces daisy-like flowers with distinctive raised central cones from mid-summer through fall. Traditional purple varieties are joined by cultivars in white, yellow, orange, and red. Extremely hardy to Zone 3, they thrive in full sun with average to poor soil. Their strong stems resist lodging, and the seedheads provide winter interest and bird food. Deadheading extends bloom time but leave final flowers for winter interest and wildlife.

Gaillardia (Blanket Flower)
These heat and drought-tolerant perennials offer bold, daisy-like flowers in hot color combinations of red, orange, and yellow from early summer until frost. Most varieties grow 18-24" tall with a spreading habit. They require excellent drainage, especially in winter, and perform best in poor to average soils with full sun. 'Arizona Sun' and 'Burgundy' are reliable Zone 4 performers. Short-lived (3-4 years) but may self-seed. Deadheading promotes continuous bloom.

Karl Foerster Grass (Calamagrostis x acutiflora)
This architectural grass forms neat, upright clumps of narrow foliage 3-4' tall, with feathery flower plumes rising to 5-6' in early summer. The plumes emerge reddish-tan, mature to golden wheat, and remain attractive through winter. Exceptionally hardy to Zone 3, it grows in full sun to part shade and tolerates heavy soils better than most ornamental grasses. One of the earliest grasses to emerge in spring, it provides vertical accent without flopping or spreading. Cut back in late winter before new growth appears.

Lavender (Lavandula)
For Zone 4, focus on the hardiest varieties: Lavandula angustifolia 'Munstead' and 'Hidcote'. These English lavenders produce fragrant purple flower spikes in early summer above silvery, aromatic foliage. They grow 18-24" tall and require exceptional drainage, especially in winter. Plant in full sun in slightly alkaline soil, ideally with gravel mulch. Avoid heavy pruning in fall; instead, trim lightly after flowering and more substantially in spring after new growth appears.

Lupine (Lupinus)
Despite not being your favorite, these distinctive perennials deserve mention for their dramatic spires of pea-like flowers in blues, purples, pinks, whites, and bi-colors in late spring to early summer. They prefer cool summers, acidic soil, and resent transplanting once established. The Russell hybrids and native Lupinus perennis are Zone 4 hardy. They form basal clumps of palmate foliage with 24-36" flower stalks. Often short-lived but may self-seed in favorable conditions.

Nepeta (Catmint)
This aromatic, drought-tolerant perennial produces lavender-blue flower spikes above gray-green foliage from late spring through summer. 'Walker's Low' (18-24") and 'Six Hills Giant' (30-36") are outstanding Zone 3 hardy varieties. They bloom heavily in early summer, with reblooming after shearing. Deer and rabbit resistant, they attract pollinators and provide soft texture in the landscape. Combine with roses, irises, and other sun-loving perennials for extended seasonal interest.

Penstemon (Beardtongue)
These North American natives feature tubular flowers on upright stems that attract hummingbirds and pollinators. Zone 4 hardy varieties include Penstemon digitalis 'Husker Red' with white flowers and burgundy foliage, and the shorter Penstemon hirsutus with lavender-purple blooms. They flower in early to mid-summer and prefer full sun and well-drained soil. Many have semi-evergreen basal foliage. Excellent for cottage gardens and naturalistic plantings.

Peony (*Paeonia* species)
These garden aristocrats deliver spectacular blooms in late spring to early summer with unforgettable fragrance. Flowers range from simple, elegant singles to fully double blooms in white, pink, coral, and deep red. Peonies are exceptionally hardy to Zone 3, living for decades with minimal care. Their glossy, deeply lobed foliage remains attractive all season, often with burgundy fall color. Plant in full sun to light shade with well-drained soil. Division is rarely needed, and they actually prefer to remain undisturbed.

Rudbeckia (Black-Eyed Susan)
These cheerful, golden-yellow daisies with dark centers provide weeks of bold color from mid-summer into fall. The most common variety, Rudbeckia fulgida 'Goldsturm', forms tidy clumps 24-30" tall and is hardy to Zone 3. Their drought tolerance, deer resistance, and long bloom season make them indispensable for sunny gardens. They combine beautifully with ornamental grasses and purple-flowering perennials. Allow seedheads to remain for winter interest and bird feeding.

Russian Sage (Perovskia atriplicifolia)
This woody subshrub creates clouds of lavender-blue flowers on silver stems from midsummer through fall. Growing 3-4' tall and wide, its aromatic, silver-gray foliage is ornamental even before blooming. Exceptionally drought tolerant once established and reliably hardy to Zone 4, it requires excellent drainage and full sun. Cut back to 6-8" in early spring rather than fall. Combines beautifully with yellow-flowering perennials and ornamental grasses.

Saponaria (Soapwort)
Saponaria officinalis produces clusters of five-petaled pink to white flowers in midsummer on 24-30" stems. While this species can be somewhat aggressive, the more garden-worthy Saponaria ocymoides (Rock Soapwort) forms a low, spreading mound (8-10") covered with bright pink flowers in late spring to early summer. Both are extremely hardy (Zone 3) and drought-tolerant once established. Rock Soapwort excels in rock gardens, wall crevices, and as a groundcover in difficult, dry sites.

Scabiosa (Pincushion Flower)
These charming perennials produce distinctive "pincushion" flowers on wiry stems throughout summer. Scabiosa caucasica varieties offer the best Zone 4 hardiness, with blooms in blue, lavender, pink, or white on 18-24" stems. They prefer well-drained soil and full sun but appreciate afternoon shade in hot climates. Deadheading significantly extends bloom time. 'Butterfly Blue' and 'Pink Mist' are reliable performers that attract pollinators and make excellent cut flowers.

Sedum (Stonecrop)
These succulent perennials come in two main types for Zone 4 gardens: upright (like 'Autumn Joy') and low-growing groundcovers. The upright varieties (18-24") develop broad, flat flower clusters in shades of pink, red, or white in late summer that persist through fall. Low-growing types form carpets of colorful, drought-resistant foliage with starry summer flowers. All require excellent drainage and full sun. Virtually maintenance-free and deer resistant, they provide outstanding late-season color and winter interest.

Veronica (Speedwell)
These versatile perennials offer spikes of small, densely clustered flowers in blues, purples, pinks, and whites from early to late summer. Veronica spicata varieties grow 18-24" tall, while V. prostrata types form low mats (4-6"). All prefer consistent moisture and good drainage but are adaptable and hardy to Zone 4. 'Royal Candles' (blue), 'First Love' (pink), and 'Sunny Border Blue' are exceptional performers. Deadhead to extend bloom time and divide every few years to maintain vigor.