Plant and Garden Reference Information

Biennial Plants

The smallest of the three major plant life cycle groups is biennial plants. These are plants that take a full two years to complete their lifecycle from germination, to flowering, to dying. Many commercially grown vegetables are biennial plants, however of these, many are forced through extreme cold cycles to speed their normal growth and complete the cycle annually. In some cases, it is possible to accelerate this cycle to three to four months if necessary. Most biennial plants will flower only once in their lifetime.

The typical life cycle for a biennial plant is to spend the first year in vegetative growth, and complete the remainder of its life in the second year. Early in spring, initiated by the winter cold cycle, these plants shoot up, flower, fruit, and seed before dying in the end of that second year. This need for the cold cycle to spur blossoming allows for the manipulation of this cycle to speed up the process.

Below is a list, by no means comprehensive, of biennial plants:

Alcea rosea (Hollyhock)
Anacyclus depressus (Mount Atlas Daisy)
Anagallis monelli (Pimpernel)
Campanula medium (Canterbury Bells)
Cheiranthus cheiri (English Wallflower)
Delphinium grandiflorum (Chinese Delphinium)
Dianthus barbatus (Sweet William)
Digitalis purpurea (Common Foxglove)
Dipascus sylvestris (Teasel)
Echium vulgare (Blueweed, Viper's Bugloss)
Exacum affine (Persian Violet, German Violet)
Limonium sinuatum (Statice, Sea-Pink, Sea-Lavender)
Lunaria annua (Honesty, Money Plant)
Matthiola incana (Queen Stock, Gillyflower, Brampton Stock)
Myosotis alpestris (Forget-Me-Not)
Onopordum acanthium (Cotton Thistle, Scotch Thistle)
Salvia sclarea (Clary Sage)
Verbascum densiflorum (Mullein)