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Perennials and Their Seasons

Summer perennial border
Colorful perennial border backed by hedge

Understanding the nature of plants will help you establish a garden that will be a thing of beauty rather than a disappointment.

Perennials are plants that live for three or more years. They live longer than annuals and biennials. Of course, trees and shrubs are perennial in habit, but the term perennial is generally applied to herbaceous rather than woody plants.

Most, but not all, perennials send up new branches and flower stems each year; these branches and stems die when winter comes, but the roots continue to live. Many of these perennials live indefinitely—some for years and years. Others tend to die out after three or four years unless the roots are taken up, divided and replanted every two or three years. The latter is known as “imperfect perennials.”

Over the generations, flower gardeners have favored hardy perennials such as phlox, peonies, delphinium, and bleeding heart. These favorites have become known as “old-fashioned” plants because of their hardiness, permanency, and variations of color, height, foliage, and nature of bloom. Old-fashioned plants are in truth the backbone of many modern gardens.

Perennials offer the gardener many advantages. First, as some perennials finish blooming, other perennials come into bloom; as the garden changes from week to week there is always something new to look forward to.

Second, while annuals blossom for long periods (which over a full season can become monotonous), few perennials bloom all season. That means with considered selection and arrangement, a diversity of perennials will assure continuous change in the garden from early spring until fall. Because of this ever-shifting picture, the perennial border has become more and more a feature of many gardens.

Perennial border in summer
Perennial border in summer

Perennials in Border Design

The perennial border is one of the most flexible parts of the garden, having no regular or formal design but lending itself to variations according to the taste of the individual gardener.

Perennials should be arranged with consideration of their size and space allotted them in the garden. Place the tallest species in the background, especially those that provide a good display of foliage. Some tall perennials should, however, extend into the front, especially in the wider parts of the border—this will provide interest and relieve any possible monotony. Small and dwarf perennials should be used in the foreground with plans to intermediate height distributed throughout the rest of the border.

If a border is devoted entirely to perennials it should be at least 5 feet wide. If the garden is small and there is a hedge or a shrub border, the space between that feature and the lawn or path can be widened by 2 or 3 feet and beautified by planting perennials in the bed.

Perennials are always best when planted in masses of clumps; these are more interesting and attractive than hit-or-miss planting, especially if consideration is given to color harmony or contrast. Generous use of white flowers is frequently advisable.

Perennials by Season

Blue forget-me-nots, Myosotis sylvatica, spring blooming
Blue forget-me-nots, Myosotis sylvatica, spring blooming

Spring-Flowering Perennials

After the earliest flowering bulbs have gone spring color depends to a large degree upon perennials. Early iris, peonies, and columbine are notable early perennials. Other early perennials are Canterbury bells, delphinium, and foxglove. Here is a list of spring-blooming perennial favorites.

Botanical NameCommon Name
 Adonis amurensisAmur Adonis
Alyssum saxatile compactumDwarf golden tuft
Arabis alpinaAlpine rock-cress
Aubreitia deltoideaPurple rock-cress
Bellis perennisEnglish daisy
Claytonia virginicaSpring beauty
Convallaria majalisLily-of-the-valley
Dicentra eximiaPlumy bleeding heart
Dicentra spectabilisBleeding heart
Doronicum caucasicumLeopards-bane
Euphoribia epithymoidesCushion spurge
Hemerocallis flavaLemon daylily
Iberis sempervirensEvergreen candytuft
Mertensia virginicaBluebells
Myosotis sylvaticaForget-me-not
Polemonium reptansCreeping polemonium
Trollius europaeusGlobe flower
Vinca minorCommon periwinkle

Summer-Flowering Perennials

As spring blossoms fade there come into flower a vase array of summer perennials which can be classified into two groups: (1) the early summer species, and (2) the late summer species.

Astilbe blooms in early summer
Astilbe blooms in early summer

Early-Summer Perennials

Botanical NameCommon Name
Anchusa azureaItalian bugloss
Anthemis tinctoriaGolden marguerite
Astilbe japonicaJapanese astilbe
Baptisia australisFalse indigo
Campanula persicifoliaPeach-leaf bellflower
Centaurea montanaMountain bluet
Coreopsis lanceolataPerennial coreopsis
Echinops ritroGlobe thistle
Geranium sanguineumCranes-bill
Geum chiloenseAvens
Gypsophila paniculataPerennial babys breath
Heuchera sanguineaCoral bells
Lupinus polyphyllusPerennial lupine
Oenothera fruticosaEvening primrose
Penstemon  varieitiesPenstemon various
Polemonium caeruleumGreek valerian
Thalictrum aquilegifoliumColumbine meadow-rue
Valeriana officinalisGarden heliotrope
Veronica spicataSpike speedwell
Yucca filamentosaCommon yucca
 Purple Coneflower is a late summer perennial
Echinacea purpurea also known as Purple Coneflower is a late summer perennial

Late Summer Perennials

Botanical NameCommon Name
Achillea millefolliumYarrow
Achillea ptarmicaSneezewort
Bocconia/Macleaya cordataPlume poppy
Campanula carpaticaCarpathian harebell
Echinacea purpureaPurple coneflower
Euphorbia corollataFlowering spurge
Gaillardia aristataPerennial gaillardia
Geranium ibericumIberian cranesbill
Hemerocallis fulvaTawny daylily
HostaPlantain-lily
Liatris pycnostachyaGayfeather
Limonium latifoliumSea-lavender
Linum perennePerennial flax
Oenothera speciosaSundrops
Platycodon grandiflorumBalloon flower
Rudbeckia laciniataCutleaf coneflower
Salvia nemerosaViolet sage
Thalictrum dipterocarpumYunnan meadow-rue
Viola cornutaTufted pansy
Black-eyed susan perennial flower
Rudbeckia hirta or black-eyed susan is a mainstay of the fall perennial garden

Fall Perennials

As summer’s heat wanes and days grow perceptibly shorter, a number of perennials come into bloom, to give the garden the benefit of their beauty and continue to blossom until frost nips them. Among fall-blooming perennials are:

Botanical NameCommon Name
Aconitum fischeriAzure monkhood
Anemone japonicaJapanese anemone
Artemisia varietiesMugwort
Boltonia asteroidesBoltonia
Chelone glabraTurtlehead
Eupatorium coelestinumMistflower
Helenium autumnaleSneezeweed
Helianthus maximilianiMaximilian sunflower
Helianthus rigidusPrairie sunflower
Hibiscus moscheutosRose mallow
Lobelia cardinalisCardinal flower
Lobelia syphiliticaBlue lobelia
Rudbeckia speciosaShowy coneflower
Salvia azureaAzure sage
Chrysanthemum varietiesChrysanthemum
Sedum spectabileShowy sedum
Candytuft Iberis evergreen
Evergreen plant Iberis sempervirens, Candytuft flowering at the garden path

Evergreen Perennials

A number of perennials retain their leaves year around. They include:

Botanical NameCommon Name
Dianthus barbatusSweet william
Dianthus plumariusGrass pink
Heuhchera sanguineaCoral bells
Iberis sempervirensEvergreen candytuft
Iris foetidissimaGladwin iris
Linum perennePerennial flax
SedumStonecrop
Teucrium chamaedrysGermander
Thymus serpyllumMother-of-thyme
Yucca filamentosaBayonet plant

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