What is a Perennial

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Botanically, any plant that lives for three or more years is a perennial.
Blooming and setting seeds is not a life ending process as it is for annuals and biennials.
This includes trees and shrubs.
So, obviously gardeners are using the word in a different way from botanists.

What we mean by “perennial”

We use the word as an abbreviation for hardy, herbaceous perennial: non-woody plants that are grown for their attractive flowers or foliage and survive winter temperatures.

Perennials for us need to:

·Survive temperatures down to 10 degrees F (north) 15 degrees F (south), but accept relatively mild winter weather.
·Tolerate 5 months of days in the 90s and nights in the 70s, high humidity, occasional drought, frequent afternoon rains and occasional deluges.

Look for plants recommended for hardiness zones 7 to 10; heat zone 9.

Success with Perennials in Louisiana depends on proper selection of perennials adapted to the Coastal South and providing proper growing conditions

These days there is far more information and focus on perennials for the Southeast than in the past.

Good Perennial References

-Garden Perennials for the Coastal South
by Barbara Sullivan
-Perennial Garden Color by William Welch
-Your Florida Guide to Perennials by Sydney Park Brown and Rick Schoellhorn
-Native Perennials for the Southeast by Peter Loewer
-Passalong Plants by Felder Rushing and Steve Bender
-Garden Bulbs for the South by Scott Ogden

More Good Sources

  • Check local sources of information
  • LSU AgCenter information
  • Knowledgeable gardeners who are growing perennials
  • Nursery staff
  • Local gardening symposia, classes, workshops

Be very careful looking at:

  • Internet information – Know the source of the information
  • Television programs
  • Often take place in different climates
  • References not written for the Deep Southeast
  • Magazines
  • Make sure the information is appropriate for our unique climate!

Planning the Perennial Garden

Planting flowerbeds with perennials is very different than using annuals.

Annuals vs. Perennials

·Annuals – removed when unattractive; Perennials – own their spot year round
·Annuals – bloom the entire season; Perennials – bloom can last a few weeks to a few months
·Annuals – have little ability to recover from adversity; Perennials – have more stamina and ability to recover from adversity

Diversity is the key to perennial gardening

·Choose perennials with various blooming times to ensure flowers over long periods; This is especially important because of our very long growing season
·Choose perennials with various growing seasons to keep the bed from looking barren at times; also make use of annuals, bulbs, shrubs and small trees
·A diverse perennial planting in Shreveport

Characteristics for Planning

·What species or cultivars of a genus are best for Louisiana
·What light conditions does it prefer
·How tall will it grow
·When how long does it bloom; what colors are the flowers
·Good drainage, average or poor
·Is it evergreen; if it goes dormant – when; texture
·How fast does it spread
·Does it provide food for butterflies or birds

Plan for Maintenance

·Perennial beds require regular watering, fertilizing, grooming, staking, deadheading, cutting back, dividing, transplanting, weeding and mulching
·Do not plant more beds of perennials than your available time will allow you to properly care for them.


·Make sure you do a good job with bed preparation – remember, these plants will live in that location without being disturbed for years
·Space plants appropriately
·Do not plant too deep
·Water thoroughly

Dividing Perennials

·Divide during the perennial’s dormant season.
·For most this is in the late fall, winter, early spring period.
·A few, notably Louisiana irises, lycoris, calla lily, Easter lily and spring flowering bulbs are dormant in summer.
·Clump of garlic chives.
·Lift clump – trowel or shovel.
·Study the clump carefully and decide how many divisions to make and where to make the cuts through the clump.
·Use a large knife to cut the clump into the desired number of divisions. Generally, not too small.
·Replant the divisions immediately, into a bed or into a container.

There are Perennials for Every Situation in the Landscape

Sunny Dry
Sunny Average
Sunny Wet
Shady Dry
Shady Average
Shady Wet


Red Yucca, Hesperaloe parviflora
Agave, Agave americana
Yarrow, Achillea millefolium
Common Yarrow Flowers
‘Strawberry Seduction’
Bearded Iris (Iris x germanica)
Red Hot Poker (Kniphofia)
Spanish Dagger Yucca, Yucca gloriosa
Yucca filamentosa 'Color Guard'
Downy Phlox, Phlox pilosa
Anise Hyssop, Agastache foeniculum 'Blue Fortune'


Swamp Mallow, Mallow, Hardy Hibiscus – Hibiscus moscheutos
Shrubby perennial 3’x3’ to 5’x5’ depending on type
Large, very showy flowers in pink, white and red
Long blooming season; tolerates wet soil
Wildlife nectar plant
Victoria Mealy Cup Sage, Salvia farinacea ‘Victoria’
Forsythia Sage, Salvia madrensis
Goldsturm Black-eyed Susan, Rudbeckia fulgida ‘Goldsturm’
Artemisia, Artemisia ludoviciana
Powis Castle Artemisia, Artemisia ‘Powis Castle’
Butterfly Weed, Asclepias curassavica
Variegated Maiden Grass, Miscanthus sinensis ‘Variegatus’
Society Garlic, Tulbaghia violacea
Speedwell, Veronica, Veronica spicata
Robert Poore Garden Phlox, Phlox paniculata ‘Robert Poore’
Miss Lindgard Phlox, Phlox carolina ‘Miss Lindgard’
Mixed Planting: Guara lindheimeri, Rudbeckia maxima


Pink Muhly Grass, Muhlenbergia capillaris
Giant black-eyed Susan, Rudbeckia maxima
Louisiana Irises, Iris spp. and hybrids
About 2’ to 5’
Very showy colorful flowers March through April
Tolerant of standing water or drier conditions
Active growth fall through spring
Spreads slowly by rhizome
Louisiana irises are most dormant during summer depending on available water.
Hymenocallis ‘Tropical Giant’
Calla Lily, Zantedeschia aethiopica
Calla lily by pond


Aspidistra, Cast Iron Plant, Aspidistra elatior
Manfreda (Agave) maculosa
Hinckley’s Columbine, Aquilegia chrysantha var. hinckleyana
Chinese Forget-me-not,
Gold Jewels of Opar (Talinum paniculatum ‘Kingwood Gold’)
Hellebore, Helleborus hybrid (orientalis)


Ligularia, Farfugium japonicum
Leopard Plant, Farfugium japonicum ‘Aurea Maculata’
Ground Orchid, Bletilla striata
Blue Walking Iris, Neomarica caerulea;
Easter Lily, Lilium longiflorum
Dwarf Monkey Grass, Ophiopogon japonicus ‘Nana’
Catlin's Giant Ajuga, Ajuga reptans ‘Catlin’s Giant
Indian Pink, Spigelia marilandica


Strawberry Geranium, Strawberry Begonia, Saxifraga stolonifera
Strawberry Geranium under Japanese Maple
Strawberry Geranium and Ivy Violet – Viola hederacea
Royal Fern, Osmumda regalis

Dan Gill
Consumer Horticulture Specialist
LSU AgCenter

3/31/2015 8:55:55 PM
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