The Green Thumb Almanac

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Perennials

What are perennials?  While annual plants live for just one year and biennials live for two, perennials are plants that live for more than two years.  Unlike trees and other woody plants, herbaceous perennials have soft stems that typically die down in winter.  Each spring their roots burst forth new leafy growth - a sight as welcome to gardeners as the blossoms of the year's first crocuses and daffodils.
 

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On This Page!

  • Perennial Plant of the Year
  • Planning Your Garden
  • Creating a Shady Oasis
  • The Sunny Border

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2017 Perennial Plant of the Year
Asclepias tuberosa - Butterfly Weed!

With all the ”buzz” about bees and butterflies, why not celebrate an excellent plant known for its ability to support insects and birds and serve as the primary caterpillar food for a beloved North American native butterfly? The Perennial Plant Association is proud to announce Asclepias tuberosa as its 2017 Perennial Plant of the Year™. 

Perennial of the year nominations are voted on by members of the Perennial Plant Association and generally need to satisfy the following criteria:  Suitability for a wide range of climatic conditions, Low-maintenance requirements, Relative pest- and disease-resistance, Ready availability in the year of promotion, Multiple seasons of ornamental  interest.

  • 1990 - Phlox stolonifera (Creeping Phlox)
    1990 - Phlox stolonifera (Creeping Phlox)
  • 1991 - Heuchera micrantha 'Palace Purple'
    1991 - Heuchera micrantha 'Palace Purple'
  • 1992 - Coreopsis verticillata 'Moonbeam'
    1992 - Coreopsis verticillata 'Moonbeam'
  • 1993 - Veronica 'Sunny Border Blue'
    1993 - Veronica 'Sunny Border Blue'
  • 1994 - Astible 'Sprite'
    1994 - Astible 'Sprite'
  • 1995 - Perovskia atriplicifolia (Russian Sage)
    1995 - Perovskia atriplicifolia (Russian Sage)
  • 1996 - Penstemon digitalis 'Husker Red'
    1996 - Penstemon digitalis 'Husker Red'
  • 1997 - Salvia 'Mainacht' (May Night)
    1997 - Salvia 'Mainacht' (May Night)
  • 1998 - Echinacea purpurea 'Magnus'
    1998 - Echinacea purpurea 'Magnus'
  • 1999 - Rudbeckia fulgida var. sullivantii 'Goldsturm'
    1999 - Rudbeckia fulgida var. sullivantii 'Goldsturm'
  • 2000 - Scabiosa columbaria 'Butterfly Blue'
    2000 - Scabiosa columbaria 'Butterfly Blue'
  • 2001 - Calamagrostis x acutiflora 'Karl Foerster'
    2001 - Calamagrostis x acutiflora 'Karl Foerster'
  • 2002 - Phlox 'David'
    2002 - Phlox 'David'
  • 2003 - Leucanthemum 'Becky'
    2003 - Leucanthemum 'Becky'
  • 2004 - Athythrium niponicum 'Pictum'
    2004 - Athythrium niponicum 'Pictum'
  • 2005 - Helleborus x hybridus
    2005 - Helleborus x hybridus
  • 2006 - Dianthus gratianopolitanus 'Feuerhexe'
    2006 - Dianthus gratianopolitanus 'Feuerhexe'
  • 2007 - Nepeta 'Walker's Low'
    2007 - Nepeta 'Walker's Low'
  • 2008 - Geranium 'Rozanne'
    2008 - Geranium 'Rozanne'
  • 2009 - Hakonechloa macra 'Aureola'
    2009 - Hakonechloa macra 'Aureola'
  • 2010 - Baptisia australis
    2010 - Baptisia australis
  • 2011 - Amsonia hubrichtii
    2011 - Amsonia hubrichtii
  • 2012 - Brunnera macrophylla 'Jack Frost'
    2012 - Brunnera macrophylla 'Jack Frost'
  • 2013 - Polygonatum odoratum ' Variegatum'
    2013 - Polygonatum odoratum ' Variegatum'
  • 2014 - Panicum virgatum 'Northwind'
    2014 - Panicum virgatum 'Northwind'
  • 2015 - Geranium x cantabrigiense 'Biokovo'
    2015 - Geranium x cantabrigiense 'Biokovo'
  • 2016 - Anemone 'Honorine Jobert'
    2016 - Anemone 'Honorine Jobert'
1990 - Phlox stolonifera (Creeping Phlox)
1990 - Phlox stolonifera (Creeping Phlox)

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Planning your perennial garden.

Planning a perennial border can be challenging.  Base your choice  of plants on the following elements:

  • Period of bloom
  • Cultural requirements (sun, soil & water)
  • Colors of flowers and foliage
  • Height
  • Spread or width
  • Shape  of plant
  • Leaf shape and texture

Since most perennials only bloom for three weeks, on average, mix in some shrubs, hardy bulbs and annuals to provide a longer more consistent show of color.

Dividing and Moving Perennials

 

Most perennials benefit from division every two to four years.  You'll know that a plant is ready to be divided if it dies out in the middle of the crown, begins to lose its vigor, starts to bloom poorly or becomes too large for its space. 

The best time to divide and move perennials are in early  spring when the new foliage reaches 2 to 3 inches high or in the fall when the foliage begins to wither.

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Create a Shady Oasis

The ideal site for your shady garden is near the edge of a high canopy of deciduous trees, which shields the garden from the scorching midday sun.  Since very few plants will do well in deep shade, try to situate your shade garden in bright, or filtered shade.  Gardening under trees can be a challenge as the trees compete with your perennials for water so apply a layer of mulch to conserve moisture. Remember to water your shade garden regularly, especially during periods of heat and drought.

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Here are a few suggestions for your shade garden:

Blue

Brunnera

Green

Hellebore

Pink

Japanese Anemone

Red

Astilbe

Violet

Liriope

White

Goatsbeard

Yellow

Columbine

Foliage

CoralBells

Foliage

Ferns

Hostas - the Queen of the Shade Garden

2017 Hosta of the Year!
'Brother Stefan'

Maybe Olga Petryszyn’s best introduction to date.  Large, heavily corrugated gold leaves with a wide dark green margin. A moderate grower which forms a spectacular specimen in due time. Near white flowers in early summer.
Photo courtesy of:  Olga Petryszyn
Hostas are a must-have for the perennial shade garden.  They are long-lived, easy to care for and generally pest and disease free.  Hostas are grouped into several categories based upon size and leaf color.  Size will vary depending upon where you live.  A hosta planted in a northern garden will grow larger than if you planted the same hosta variety in a southern garden.  In general the following chart lists the categories of hostas:
Size
 North
 South
Mini
  up to 8"
  up to 7"
Small
  9-14"
  8-11"
Medium
  15-22"
  12-18"
Large
  23-29"
  19-24"
Giant
  30" & above
  25" & above
Information courtesy of the American Hosta Growers Association

Blue

Green

Yellow

Variegated Edge

Variegated Middle

Misted or Streaked

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The Sunny Border

The Big 3!  While there are literally thousands of perennials from which to choose, try starting with the big three; daylilies, bearded iris, and peonies!  These are the plants that flourished in your grandma's garden and are great for those areas in your garden where nothing seems to grow!

Daylilies

German Bearded Iris

Peonies

 

Ornamental Grasses

Ornamental grasses add movement and texture to the perennial garden.  Explore our Plant Library to learn more about the different types of ornamental grasses.
Fountain Grass,
Pennisetum
sp.
Maiden Grass,
Miscanthus
sp.
Feather Reed Grass, Calamagrostis sp.

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