In the plant world, some
species have a two year life cycle. They
germinate and develop a set of leaves called
a rosette the first year. They survive the
winter and in the second year, the plants
develop a flower, go to seed and die. These
plants are called
biennials.
Of course, like many things in nature, there
are always a few twists in the story. If the
plants are under some type of stress such as
drought or unusual temperature extremes
during the first season, they may "decide"
to flower. This is called "bolting" and it
is not desirable in the many vegetable crops
that are biennials such as cabbages.
However, since flower
gardeners like to see flowers, bolting is
actually encouraged on ornamental species.
So, those biennial foxgloves (Digitalis
purpurea), you will find many of
them blooming during the first season.
Our index of plants
commonly grown as
biennials contains many of those used in the home landscape.