Sarah Williams Notes from May 29, 2014 Okanagan College Lecture

Perennials: Basic & Beyond & Design

I. Introduction

A matter of definition: what are perennials?

- non-woody plants which live 3 or more years

Why Perennials?

extended growing season

sense of seasonality

reduced plantings each year (maybe!)

$ ????

Selection criteria:

- hardy to zone in which planted

- long-lived

- “well behaved” (non-invasive, low maintenance)

- relatively long period of bloom

- other landscape value (foliage, seeds)

- drought tolerant

Think Foliage! (color, texture) [‘Brim Cup’ hosta, Ligularia, Pulmonaria, Megellan wheat grass]

Obtaining Perennials

buy locally

buy by mail order

grow from seed

plant exchanges: Saskatchewan Perennial Society, hort society or garden club

join botanical gardens or specialized societies for seed or plants

Location

Gardener’s point of view:Easily seen!

Perennials’ point of view:

* sun/shade

* moisture requirements

* avoid root competition

* drainage

* snow cover

Soil preparation:

Control weeds

Dig deeply

Organic soil amendments

soil amendments :

sandy soil - add organic matter (peat moss, well rotted manure, compost)

clay soil - add coarse, sharp or builders sand with organic matter

- thoroughly incorporate amendments; do not leave layered

Berm for better drainage (add organic matter; monitor moisture)

mulching - applying a “permanent” 4-inch layer of organic material to the soil surface between (not on top of) perennials, topping it off every 2 or 3 years as needed

Materials: grass clippings/coarse peat moss; wood chips; post peelings; flax straw

Benefits: water conservation, reduced weeding, reduced soil compaction, design function, adds nutrients on decomposition

Fall House-keeping and the Perennial Border

- remove diseased foliage (mildew: monarda, delphiniums)(botrytis: lilies, iris, peonies)

- divide peonies, lilies

- edge interface of lawn/border

- leave dead foliage to catch snow, insulate crown

Spring:

- remove old foliage, dead plants

- divide most perennials

- plant/transplant

- stake taller or sprawling plants

Fertilizer - apply in early spring as new growth emerges

Options:

- granular - 11-48-0, 10-51-0, 16-20-0

- water soluble with micro-nutrients

- “organic” (slow release, not instant

- nutrients released from soil amendments and mulch

* nutrient needs of perennials differ (pussy toes vs. delphinium)

What the numbers mean:

- Nitrogen (N) - leafy, vegetative growth

- Phosphorus (P) - stem, root, flower, seed

- Potassium (K) - “stress”, flower color

Water:

* established border: deeply but less frequently (every 7-10 days to a depth of 12+ inches)

* new divisions, seedlings, young plants: frequently enough to prevent them from drying out

II. Perennials as groundcovers (How much lawn do you really need?)

thyme

Waldsteinia

Whitley’s veronica

Solomon’s seal

cliff green

bergenia

‘Beacon Silver’ lamium

‘White Nancy’ lamium

‘Herman’s Pride’ lamiastrum

III. Perennials for a sunny border

‘Brandon Glow’ coral bells

‘Northern Fire’ coral bells

‘Brandon Pink’ coral bells

Siberian avens

‘Dropmore Blue’ catmint

Siberian iris

delphinium (new Millenium series)

doronicum

pink oriental poppy

day lilies

peonies (single flowered and species)

intermediate bearded iris (‘Red Heart’, ‘Princess Louise’, ‘Vice Admiral’)

perennial alyssum

Clematis recta

‘Goblin’ gaillardia

‘Max Frey’ perennial geranium

IV. Perennials for shade

Hostas (‘Lemon Lime’, ‘Brim Cup’, ‘Patriot’)

monkshood

white fan columbine

lady’s mantle

dusty miller primrose

Trollius globe flower

Ligularia

Bleeding heart (pink, white)

Lungwort

V. Beyond basic Perennials:

Extending the Season: The Early

Soft lungwort (Pulmonariamollis)

Cortusa primrose (Primulacortusoides)

English cowslip (Primulaveris) – try ‘Sunset Shades’

Primulamarginata

Corydalis nobilis – dormant in summer

Hepatica

Marsh marigold (Calthapalustris)

Spring Adonis (Adonis vernalis)

European pasque flower (Pulsatilla vulgaris)

Extending the Season: Late Summer/fall

‘Terracotta’, ‘Paprika’ yarrow (Achilleamillefolium)

‘Summer Pastels’ (cream selection)

‘Credo’ yarrow (Acilleamillefolium)

Anemone tomentosa ‘Robustissima’

Taller Sedums (‘Frosty Morn’, ‘Brilliant’, ‘Autumn Joy’)

Gaining altitude: the Tall

Goat’s beard (Aruncusdioicus)

White fleece flower (Persicariapolymorpha)

Bugbane (Cimicifugaracemosa)/ Cimicifuga simplex ‘Brunette’

Joe Pye weed (Eupatorium purpureum; syn. E. maculatum)

Ornamental rhubarb (Rheum palmatum)

Think Foliage! Grasses, ferns and perennials

Blue lyme grass

Blue oat grass (Helictotrichonsempervirens) (longest lived of blue clumping grasses)

‘Skinner’s Blue’ fescue

‘Karl Foerster’ feather reed grass (Calamagrostis x acutiflora)

‘Beatles’ carex (Carexcaryophyllea)

‘Blue Zinger’ blue sedge (Carexflacca)

palm sedge (Carexmuskingumensis)

Bowles goldengrass (Milliumeffusum ‘Aureum’)

frost grass (Spodiopogonsibiricus)

tatting fern (Anthyriumfilix-femina ‘Frizelliae’)

‘Lady in Red’ fern (Anthyriumangustum, forma rebrellum)

rockpolypody fern (Polypodiumvirginianum)

Rogers flower (Rogersiaaesculifolia)

‘Gold Heart’ bleeding heart (Dicentraspectabilis)

bishop’s cap (Epimediumgrandiflorum)

variegated horseradish (Armoracialapathifolia)

European ginger (Asarumeuropeum)

Iris species – Try them!

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Yellow flag iris (Iris pseudacorus)

Blue flag iris (Iris versicolor)

Arctic iris (Iris setosa)

Milk iris (Iris lacteal)

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VII. Design and Colour in the Perennial Border

I. Origin of modern Perennial Borders:developed as backlash to elaborate geometric Victorian “bedding-out” of annuals

  • critics wanted hardy herbaceous material in more informal design

William Robinson (Gravetye Manor) – admired cottage gardens of rural England that were “never bare and seldom ugly”

Gertrude Jekyll –Pioneer of modern colour schemes; worked with Edwin Lutyens, architect, who designed formal gardens and hardscape in which she planted cottage-style borders that overflowed and softened the geometric framework

II. Designs for Perennial or Mixed Borders

  • double long border
  • single long border – backed by hedge or wall
  • curved border
  • island beds - (Alan Bloom, Bressingham Gardens and Nursery)

Other Design uses of perennials:

  • garden rooms – space delineated by trees and shrubs or walls, fences and pergolas
  • ground covers – replacing odd bits or strips of lawn with tough perennial groundcovers adapted to specific microclimate
  • pavement plantings – among bricks or paving stones to soften hardscape

Smaller borders

  • select plants carefully to provide a long season of interest
  • more emphasis on foliage and inclusion of dwarf shrubs

III. The Mixed Border - the addition of annuals, biennials, hardy and tender bulbs, vines, ornamental grasses, small trees and shrubs

  • extends season
  • greater interest in terms of height, form, color and texture

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Dwarf deciduous shrubs for the mixed border:

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‘Rose Glow’ barberry

‘Sunsation’ barberry

‘Walker’ caragana

‘Lorbergii’ caragana

Silver Charm’ dogwood

‘Ivory Halo’ dogwood’

Cotinus

‘Toba’ hawthorn

February daphne

‘Carol Mackie’ daphne

rosedaphne

‘Annabelle’ hydrangea

‘PeeGee’ hydrangea

‘Mango Tango’ potentilla

‘Primrose Beauty’ potentilla

double flowering plum

Spireatrilobata

‘Goldflame’ spirea

‘Goldmound’ spirea

‘MiniSunglow’ spirea

cistena cherry

‘Meyer’ lilac

‘Goldflame’ spirea/dwarf cranberry

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Dwarf Conifers for the mixed border

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Mugo pine

‘Ohlendorfii’ dwarf spruce

‘Little Giant’ cedar

‘Globosa’ dwarf blue spruce

subalpine fir

weeping Norway spruce

weeping blue spruce

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Hardy Bulbs for the Mixed Border:

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Allium flavum

Allium karataviense

Fritillariamelagris

‘Dancing Eye’ lily

‘Dynamico’ lily

‘Monte Negro’ lily

Puschkinia

Muscari (grape hyacinth)

Scillasiberica

Tulipaurumiensis

Tulipatarda

Tulipagregii “Red Riding Hood’

‘Golden Apeldornm’ tulip

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IV. Other Elements to Consider:

Spacing –look on planting tags or consult reference books for mature size/spacing

  • budget versus patience

Height

  • shorter plants toward front
  • taller plants toward back
  • avoid rows and regimentation

Repetition

  • does not imply mirror image or symmetry
  • repetition of larger “groupings” of species or cultivars to provide a sense of unity.

Diagonal drifts

  • a colour grouping that appears to drift diagonally from the front to the rear of the border( rather than a large rectangular block)
  • plants that die back in mid-season (Oriental poppies)

V. Color Schemes

Color and language - our words for colours lack precision

Colour in plants

  • varies with soil, nutrition, water, light, shade and general growing conditions
  • neighbouring plants influence our perception of a plant’s colour

Color wheel

  • represents our perception of visible light
  • invented by Issac Newton (1642-1727)

Polychromatic colour scheme – all colours

Complementary colour scheme - colours opposite each other on the colour wheel

-blue/ yellow

-Tulipatarda/Siberian sqill

-Daylily/perennial geranium

-Veronica/tobacco plant

-Sedum/clustered bellflower

-‘Gold Flame’ spirea/blue lyme grass

-Allium krataveniensis/tulip/globe flower/Juniperuscommunis ‘DepressaAurea’

Analogous colour schemes

  • colours next to each other on the colour wheel
  • cream/yellow/orange

lilies/poppies/Verbascum

-daylily

-doronicum/Siberian avens

-calendula/daisies

-rough heliopsis/Ohio buckeye (fall color)

Monochromatic colour scheme

  • only one colour, but in all its tints and shades

- tint: add white to a colour (red + white = pink)

- shade: add black to a colour (red + black = maroon)

- tone: add both black and white to a colour (red + black & white = rose)

* a pure colour harmonizes with its tints, shades and tones

-calla lily/bleeding heart/liatris

-lupines/lungwort/salvia

-gas plant

-lungwort

- peonies/allium

“Colour Echo” – (Pamela Harper): colourof one plant repeated in another to create interest and unity

-‘Brunette’ Cimicifuga/Acidanthera

-bleeding heart/hosta

-iris/thyme

-salvia/iris

-daylily/allium

-coral bells/columbine

-tulip/barberry/bergenia

-iris/clustered bellflower; dogbane/hosta

Pastels – pinks, blues, pale yellows, greens

  • subtle, always “work”; easiest for beginner
  • appear to retreat

Hot colours– gold, red, yellow, orange, scarlet (also luminous white)

  • lend a feeling of warmth
  • advance and come forward
  • pastel border and “hot” border generally separated (use dwarf evergreen shrubs)

VI. Some Color Samplers

Blue

  • cool colour
  • visually drops back and appears more distant; increases feeling of spaciousness
  • may need pale yellow, silver of white to show up
  • need large masses to make impact (foliage of hostas)

-hosta ‘Blue lake’

-Puschkinia/Siberian squill

-gentian

-Hosta/allium

-Hosta/forget-me-not

-Hosta/Veronica ‘Trehane’

-Hosta/lady’s mantle

-Hosta/trollius

Silver-Grey

  • intermediate between black and white
  • harmonizer, calms, blends
  • always an intricate part of a white garden

-Salvia officinalis

-Russian oilive/Cerastium

-‘Zempen’ wolf willow/yellow daylilies

Pink (Artemisia ‘Silver Brocade’/allium)

  • pastel or tint when white is added to red
  • easy, comforting, calm, soothing, non-threatening
  • shows up well in shade; may appear bleached or faded in full sun

- peony ‘Tinka Phillips’

-Astilbe

-Iris/babysbreath/achillea/alpinedaisy/clustered bellflower

-Tulips/alliums

-Salvia/Persian cornflower/perennial geranium

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