Annual or Perennial?

There seems to be a widespread belief, especially in the US, that plants are either annuals or perennials depending on where you grow them. There are a lot of perennials that we usually grow as annuals, either because they do better in their first year, or because they aren't hardy in most gardens where they're grown, but that doesn't alter the fact that they are really perennials.

Given their perfect growing conditions, perennials will grow for several years. Given perfect growing conditions, annuals will die after they flower and set seed in their first year.

Here's a list of plants often considered to be annuals and usually grown for only one year, with their correct botanical classification according to the Royal Horticultural Society/American Horticultural Society A-Z Encyclopaedia of Garden Plants.

Annual Perennial
Ageratum houstonianum - Floss Flower
Ammobium alatum - Winged Everlasting
Argemone mexicana - Mexican Prickly Poppy
Asperula orientalis - Woodruff
Borago officinalis - Borage
Brachycome iberidifolia - Swan River Daisy
Browallia americana
Calendula officinalis - English Marigold
Callistephus chinensis - China Aster
Campanula medium - Canterbury Bells
Centaurea cyanus - Cornflower, Bachelor's Buttons
Clarkia amoena - Clarkia, Godetia
Cleome hassleriana - Spider Flower
Consolida ajacis - Larkspur
Coreopsis californica
Cosmos bipinnatus - Cosmos
Cosmos sulphureus - Cosmos
Felicia bergeriana - Kingfisher Daisy
Felicia heterophylla
Gaillardia pulchella - Blanket Flower
Helianthus annuus - Sunflower
Iberis umbellata - Candytuft
Ipomoea coccinea - Red Morning Glory
Ipomoea purpurea - Morning Glory
Lathyrus odoratus - Sweet Pea
Lavatera trimestris - Mallow
Moluccella laevis - Bells of Ireland
Nemesia strumosa
Nemophylla - 5-spot
Nicotiana langsdorfii - Flowering Tobacco
Nigella - Love in a Mist
Papaver rhoeas - Field Poppy
Papaver somniferum - Opium Poppy
Phacelia campanularia - Californian Bluebell
Phlox drummondii - Annual Phlox
Salvia viridis - Annual Clary
Sanvitalia procumbens - Creeping Zinnia
Schizanthus pinnatus - Poor Man's Orchid
Tagetes - African or French Marigold
Tithonia - Mexican Sunflower
Torenia fournieri - Wishbone Flower
Tropaeolum majus - Nasturtium
Tropaeolum peregrinum - Canary Creeper
Zinnia elegans - Zinnia
Antirrhinum majus - Snapdragon
Arctotis fastuosa - Cape Daisy
Arctotis venusta - Blue-eyed African Daisy
Bellis perennis - English Daisy
Browallia speciosa - Bush Violet
Calandrinia grandiflora
Campanula, most - Bellflower
Catharanthus roseus - Vinca
Celosia argentea - Cockscomb
Cobaea scandens - Cup and Saucer Vine
Craspedia globosa - Drumsticks
Dianthus barbatus - Sweet William
Dianthus chinensis
Erysimum cheiri - Wallflower
Felicia amelloides - Blue Daisy
Gaillardia grandiflora - Blanket Flower
Gaillardia aristata - Blanket Flower
Gazania rigens - Treasure Flower
Gerbera jamesonii - Transvaal Daisy
Glaucium flavum - Yellow Horned Poppy
Heliotropium arborescens - Cherry Pie
Impatiens walleriana - Busy Lizzie
Ipomoea alba - Moonflower
Ipomoea lobata - Spanish Flag
Lablab purpureus - Hyacinth Bean
Limonium sinuatum - Sea Lavender
Lobelia erinus - Trailing Lobelia
Lophospermum erubescens - Creeping Gloxinia
Matthiola incana - Stock
Mimulus x hybridus cultivars
Mirabilis jalapa - 4 o'clock, Marvel of Peru
Nicotiana alata - Flowering Tobacco
Papaver nudicaule - Icelandic Poppy
Pelargonium - Geranium
Pericallis x hybrida - Cineraria
Petunia cultivars - Petunia
Ricinus communis - Caster Oil
Salvia splendens - Scarlet Sage
Salvia, most species - Sage
Solenopsis/Isotoma/Laurentia axillaris
Solenostemon scutellariodes - Coleus, Flame Nettle
Thunbergia alata - Black-eyed Susan Vine
Verbena x hybrida cultivars - Verbena
Viola x wittrockiana - Pansy

Perhaps part of the problem lies with the use of common names. Sometimes, some members of a genus are annuals, while others are true perennials. Perhaps using just a common name like Poppy or Sage and being familiar with only one or two members of the genus might lead you to suppose that all members of that genus are annual or perennial, whichever your local plant is. As you can see from the list, though, there are many plants that have both annual and perennials in the genus.

If you want to extend the range of plants in your garden, you can certainly try growing plants which aren't normally hardy over the winter in your area, and you might find some you thought were only annuals stay with you for more than one year. This isn't because you've changed an annual into a perennial, it's because you've managed to find the conditions which suit a plant which is, by nature, a perennial.


Other entries with information on this topic

Common Names and the Latin names of some popular garden plants
Common Names Index - the common names of plants mentioned in these pages, with their Latin name
Latin Names - the meanings of some common Latin botanical names
Plant Families - an introduction to Plant Families

Back to the Index of Technical Terms