Picking Plants for Knee-to-Thigh-High: Medium-Sized Perennials

Medium-sized perennials make for stand-out borders. But that's not all they're good for. Learn more about their design uses, as well as color and other options, here.

Excerpted from Garden Design
  • Colorful Greek Yarrow

    Greek Yarrow

    Greek yarrow's large, creamy-yellow flowerheads appear in summer and fall, providing perfect landing pads for beneficial insects. Greek yarrow will grow to 24 inches tall and 18 inches wide when planted in ideal conditions: full sun and well-drained or moist soil.

  • Goodness of William Guiness


    There are many columbines to choose from, but the exquisite colors of 'William Guiness' (shown here against a background of hosta) make it a popular choice for cottage gardens or mixed borders. Columbine will grow to 36 inches tall and 18 inches wide in ideal growing conditions: full or partial sun and well-drained or moist soil.

  • Silver Queen is Low Growing Ground Cover

    White Sagebrush

    This plant of many names - white sagebrush, Louisiana sagewort, silver wormwood, western mugwort - is grown predominantly for its downy silver leaves, which look great in a mixed border or a white and silver garden plan. Brownish-yellow flowerheads emerge from midsummer to fall. Plant white sagebrush in well-drained soil where it will receive full sun and watch it grow to 30 inches tall and 24 inches wide.

  • Textural Hart's Tongue Fern


    Ferns are a great, diverse group with colors, shapes and sizes to suit almost any garden.

    Shown here, the wavy-edged Hart's tongue fern is evergreen, making it an asset year-round. The large, finely cut fronds of the lady fern spring from stalks which are sometimes red-brown. For even more exciting coloring, go with the Japanese shield, or autumn fern, whose coppery-red lacy fronds turn pink and then silvery-green with age.

    Although these ferns range widely in size - from 12 inches to 4 feet tall, and 16 to 36 inches wide - they all need protection from the sun. Plant ferns in moist soil and partial or, ideally, dappled, shade in a woodland setting.

  • New England Aster Brings Distinct Color to Garden


    Asters are a favorite high-producing perennial. New England varietal 'Andenken an Alma Pötschke,' shown here, bears rich pink blooms from late summer to mid-fall. It looks great in a mixed planting, for example with 'White Heather's small daisy-like flowers. Plant asters in well-drained or moist soil with exposure to full or partial sun to achieve their best growth of up to 4 feet tall and 24 inches wide.

  • Cluster Bellflower Bears Deep Purple Blooms


    The dangling flowers of bellflowers add a unique accent to any garden. The deep purple flowers of 'Superba,' shown here, bloom throughout the summer; this variety is vigorous and can even be invasive. 'Burghaltii,' on the other hand, has a shorter season in midsummer, and a more delicate and romantic look when its lavender-colored bells open against a background of heart-shaped leaves.

    Bellflowers prefers neutral to alkaline soil that is well-drained to moist and exposed to full or partial sun. Bellflowers also do well in large containers. They can grow to 24 inches tall and indefinite width.

  • Wyevale Clematis


    While clematis are often thought of as climbing plants, their freestanding varietals shouldn't be overlooked. The variety 'Wyevale,' shown here, grows to 4 1/2 feet tall as a freestanding shrub and produces clusters of pale blue, scented blooms and fluffy, decorative seedheads. The perennial clematis integrifolia produces mid-blue flowers with slightly twisted petals and silvery seedheads; it grows to 24 inches tall and 24 inches wide, and may need supporting. Clematis prefers a chalky, well-drained soil with exposure to full or partial sun.

  • Dutchman's Breeches' Blooms Resemble Pantaloons

    'Alba' Bleeding Heart

    When in bloom, the graceful, arching stems of bleeding heart - here, 'Alba' - look like a miniature clothesline, with tiny, pale unmentionables fluttering off its 4 feet tall frame. Bleeding heart will tolerate some sun if the roots are kept moist.

  • Fantastic Strawberry Foxglove


    Foxgloves' clusters of tubular flowers sweeten up any garden with moist soil and exposure to partial sun. Strawberry foxglove, shown here, draws bees to its large pink blooms in late spring and early summer; it grows to 36 inches tall and 12 inches wide. The larger yellow foxglove, which grows to 3 feet tall and 18 inches wide, forms boasts even larger flowers with speckled throats, surrounded by with glossy leaves. Both variants do well in speckled shade and sheltered areas of the garden.

  • Tall Mass of Yellow Blooms


    With unusual, long-lasting flowers in a mixture of greens and reds and an adaptable habit tolerant of a range of conditions, Martin's spurge, shown here, is a welcome addition to any yard. To make a really dazzling planting, mingle it with only high-performing spurges: 'Dixter's copper-tinted, dark green leaves and orange bracts and E. schillingii, with its pale yellow flowerheads, to name a few.

    Spurges prefer dappled shade and well-drained to moist soil. Depending on the variety, it can grow to 3 feet tall and 3 feet wide.

  • Fresh Apple Scented Nimbus Cranesbill


    Happy looking geraniums brighten up shady areas. Shown here, the high-producing 'Nimbus' blankets its surrounds with lavender-blue flowers in summer and can be clipped to encourage repeat flowering. Vigorous 'Brookside' takes 'Nimbus's best attributes one step further, to make a vigorous purple-blue ground cover.

    Another good ground cover is bigroot geranium (also known as bigroot cranesbill), whose strongly aromatic, sticky leaves turn an attractive red in the fall after its flat pink flowers have finished their season. Or, for one of the easiest varieties around, go with Mourning Widow (or, dusky cranesbill), whose dark maroon flowers will tolerate more sun than most geraniums.

    Generally, geraniums prefer partial sun or full shade, and well-drained soil, and grow to around 30 inches tall and 18 inches wide, but variations occur so make sure to check the label.

  • Baby's Breath

    Baby's Breath

    Baby's breath creates a cloud of blossoms as its many tiny white flowers emerge in midsummer. It looks marvelous in a mixed border and also provides good cut flowers. Plant baby's breath in ideal growing conditions - full sun and well-drained soil - and watch it grow to 4 feet tall and 4 feet wide.

  • Garden of Helenium Moerheim Beauties


    Sneezeweed's funny name matches the whimsy of its flowers, which look skirted and wide-eyed. The copper-red blooms of 'Moerheim Beauty,' shown here, fill a garden with warm summer color; deadhead them to encourage repeat flowering. Sneezeweed will grow to 36 inches tall and 24 inches wide when planted in ideal growing conditions: full sun and well-drained or moist soil.

  • Distinctive Stinking Hellebore


    Hellebores are great assets for maintaining winter interest in gardens. Be careful not to trample the stinking hellebore, shown here, or you'll understand where it gets its name; instead, admire its greenish-white flowers from afar. Other good varieties include the Wester Flisk Group, with red-tinted main stems, and the Corsican hellebore, whose glossy leaves surround pale green blooms. Hellebores can grow to to 4 feet tall and 36 inches wide in most conditions, particularly full or partial sun and moist soil, but they cannot abide acidic soils.

  • Buzz Bomb is Lively Flowered Day Lily


    Daylilies brighten up any border. The large, bright orange 'Buzz Bomb,' shown here, reaches for the sun over a long season. For a lighter option, go with the lemon-yellow 'Marion Vaughn,' which looks particularly good in a drift with other daylilies. Daylilies grow to 34 inches tall and 30 inches wide, and crave full sun and well-drained or moist soil.

  • Royal Standard Hosta is Fragrant


    Hostas inject lush, dense foliage into any area that has well-drained or moist soil and partial sun. They look lovely when varietals are mixed and they also do well in containers.

    Fast-growing, vigorous 'Royal Standard,' shown here, has well-ribbed pale green leaves that contrast nicely with its funnel-shaped, fragrant white flowers. For a different color combination, consider the olive-green heart-shaped leaves and lavender-blue flowers of 'Francee.' Plant the large, dramatic 'Elegans' in a slightly sunnier area to bring out the color of its blue-green leaves and lilac-colored flowers.

    Different kinds of hostas grow to different sizes - up to 4 feet tall and 4 feet wide - so be sure to check labels when purchasing.

  • Wild-Growing Knautia

    Knautia macedonica

    Knautia macedonica's purple-red pincushion flowerheads stand up above the foliage from mid- to late summer, where they can best attract bees and butterflies. Fairly drought-tolerant and partial to full sun and well-drained soil, knautia macedonica is ideally suited to a wildflower or cottage garden where it can stretch to 32 inches tall and 18 inches wide.

  • Bees Sunset Torch Flower has Architectural Appeal

    Red Hot Poker

    Also known as torch lily, red hot poker has an aptly named, spicy look. 'Bees' Sunset,' shown here, sports yellow-orange tubular flowers atop fleshy stems which grow to 36 inches tall for a long summer season. For a different color combination, go with the unusual greenish-yellow flowers of 'Percy's Pride'; at 4 feet tall it adds dimensionality to a border. Red hot pokers prefer full or partial sun, and well-drained or moist soil.

  • Chandelier Lupine


    Depending on how much space you have, lupines look lovely grown in mixed-color drifts, in a mixed or herbaceous border or in a cottage-style or informal garden design. They grow to 36 inches tall and 30 inches wide in ideal growing conditions: full or partial sun and well-drained soil.

  • Feuerkerze Loosestrife Boasts Vivid Blooms

    'Feuerkerze' Purple Loosestrife

    Masses of tiny star-shaped, intensely red-purple flowers cover the slender upright spikes of 'Feuerkerze' purple loosestrife, which rise to 36 inches tall from midsummer to early fall. The plant needs moisture and full sun; it suits a damp border or bog garden.

  • Bee Balm Attracts Variety of Pollinators to Garden

    Bee Balm

    Bee balm, also known as bergamot, is grown for its long-lasting, colorful flowers which attract bees and butterflies from midsummer to early fall. 'Squaw,' shown here, is particularly striking, with bright scarlet flowers and dark bracts. Bee balm grows to 4 feet tall and 18 inches wide in ideal growing conditions: full or partial sun and well-drained or moist soil.

  • Giant Catmint


    Catmint is a vigorous, fragrant perennial irresistible to cats and insects alike. 'Six Hills Giant,' shown here, bears masses of lavender-blue flowers throughout the summer months. Be prepared for it to take up some space in the border - up to 36 inches tall and 24 inches wide. For a different color scheme and smaller footprint, go with the pale mauve-pink 'Dawn to Dusk.' Catmint favors full or partial sun and well-drained soil. To rejuvinate it in the spring or fall, divide clumps.

  • Magnificent Marjoram

    'Herrenhausen' Oregano

    'Herrenhausen' oregano is a strongly aromatic plant with purple-flushed young leaves and bright clusters of pink flowers from late spring to fall. It's suited to a herb garden or border margin where it can get full sun and well-drained soil. 'Herrenhausen' oregano will grow to 24 inches tall and 18 inches wide.

  • Double Peony Bloom

    'Sarah Bernhardt' Peony

    There are more than 5,000 peony cultivars. The large, powder-pink, showy blooms of 'Sarah Bernhardt' are magnificent in summer bouquets; they are also so heavy that they need support. Plant 'Sarah Bernhardt' peonies in full or partial sun and well-drained soil or moist soil, where they will reward you by growing to 38 inches tall and 20-28 inches wide.

  • Black and White Oriental Poppy Makes Impact

    'Black and White' Oriental Poppy

    The large, ruffled papery white petals and dark stamened center of the 'Black and White' Oriental poppy make a dramatic impact. This cultivar reaches to 36 inches tall and 36 inches wide in ideal growing conditions: full sun and well-drained soil.

  • Andenken an Friedrich Hahn is Long Blooming Hybrid


    The hardy, vigorous, bushy 'Andenken an Friedrich Hahn' beard-tongue bears elegant spikes of bright garnet-red flowers above masses of narrow green leaves from midsummer through to mid-fall. Deadheading will significantly prolong the flowering display. 'Alice Hindley,' is another favorite; its reliable foxglove-like lilac-blue flowers open in succession along upright stems from midsummer to fall. Beard-tongues will grow to 36 inches tall and 24 inches wide in preferred conditions: full or partial sun, and well-drained and well-fed soil.

  • Red Fleeceflower


    'Firetail' smartweed, shown here, is a robust, undemanding semievergreen perennial. From midsummer to early fall, tall, rigid stems bearing small, bright red bottlebrush flowers poke up from the lush green foliage. For a softer look, go with the 'Superba,' whose pink, miniature blooms present a good show from summer through fall. Grow them together as border plants for interesting contrast.

    While 'Firetail' will grow to 4 feet tall and 4 feet wide, 'Superba' stays down at 36 inches tall and 36 inches wide. Plant them in full or partial sun and well-drained or moist soil; divide vigorous clumps in spring or summer to control their growth.

  • Jerusalem Sage

    Jerusalem Sage

    Not a real sage, the Jerusalem sage (also known as hardy or sticky Jerusalem sage) looks very effective grown in a large group in a border. Cut stems of its pale yellow flowers are good for dried arrangements. Plant Jerusalem sage in well-drained soil with exposure to full or partial sun, and watch it grow to 36 inches tall and 30 inches wide.

  • Balmoral Garden Phlox Creates Showy Floral Display


    Sweetly scented perennial phlox is a staple of the traditional cottage garden, grown for its late summer and early fall flowers. The vigorous, herbaceous cultivar 'Balmoral' has large trusses of pale pink, flattened flowers, and is a good choice for a mixed border. For a variegated form go with 'Norah Leigh,' whose tapering leaves are green-splashed creamy-white and whose long-bloming clusters of pale lilac flowers have deeper pink centers.

    Plox grows to 36 inches tall and 24-39 inches wide in ideal growing conditions: full sun and rich, moist soil.

  • Scarlet Cinquefoil forms Mounding Groundcover

    Ruby Cinquefoil

    Cinquefoils have attractive leaves, but they are mainly grown for their bright, saucer-shaped flowers, which vary from yellow through to rich red and bloom over a long season. The plants thrive in a cool, bright positions, in well-drained soil. Given the chance, they'll grow to 18 to 36 inches tall and 24 inches wide.

  • Golden Cone

    Black Eyed Susans

    Orange coneflowers, better known as black eyed Susans, are popular late-season plants, producing large quantities of yellow flowerheads with dark eyes from late summer to mid-fall. For variety's sake, plant them with other coneflowers, which provide sprightly pops of color to any mixed border, cottage garden or cut flower arrangement: 'Goldquelle' coneflower, whose yellow blooms are doubled, the narrow orange petals of 'Art's Pride' or 'Alba,' which produces large white petals around a central yellow cone from midsummer to fall. Or, plant them verbena and grasses in a border.

    Coneflowers grow to between 3 and 5 feet tall and 18 inches wide in ideal growing conditions: full sun and well-drained soil.

  • Flowering Matrona

    'Matrona' Sedum

    The 'Matrona' sedum's flattened heads of tiny pink star-like flowers sit against fleshy leaves and dark red stems in the summer. In winter, its dried flowerheads add structure and interest. The 'Matrona' sedum will grow to 24 to 30 inches tall and 12 to 18 inches wide in ideal growing conditions: full sun and well-drained soil.

  • Aunt May Blooms Resemble Irises

    'Aunt May' Satin Flower

    An excellent front-of-the-border plants, in summer the 'Aunt May' satin flower bears small yellow flowers above its cream-edged, gray-green, narrow leaves. It also suits a gravel garden. 'Aunt May' satin flower grows to 20 inches tall and 10 inches wide in full sun and well-drained soil.

Excerpted from Garden Design

©Dorling Kindersley Limited 2009

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