Generally, biennial flowers are plants that survive two growing seasons. In the first year, biennials produce rosette-shaped foliage; they bloom flowers in the second growing season. However, some biennials, such as foxgloves, may bloom in their first year while others may survive more than two years and are called "weakly perennials.". Plant biennial seeds in a shady part of the garden after the first frost. Water well until they germinate. When the seedlings are well established, transplant them to a sunnier area.
Foxgloves (Digitalis species) can grow from 3 to 6 feet tall. The basal rosette of lance-shaped and hairy leaves grow up to 1 foot. A spike of flowers develops in the second season, or, infrequently, the first. Digitalis purpurea blooms to create tubular purple flowers with internal white and black spots. These flowers are approximately 1-inch long. Digitalis lanata produces slightly smaller flowers that are yellow to brown. These flowers have a lower protuberance that makes them look like they are sticking their tongues out. Foxgloves contain glycosides and digoxin, key ingredients in pharmaceuticals. When harvested casually and ingested improperly, humans can suffer from poisoning.
Pansies (Viola species) are members of the violet family. They may be grown in planters or your flower bed. They come in a variety of colours, such as yellow, orange, purple, violet and blue. Each flower has five petals: two upper petals and three lower petals. The plants grow up to 9 inches high and the flowers three inches across. In zones 9 to 11, where temperatures do not dip below -6.67 degrees Celsius, they may stay in bloom for the entire second year. Pansies can grow as far north as zone 4.
Evening primroses (Oenothera officinalis) are hardy plants that grow in a variety of temperature and soil conditions. Their yellow blooms open mostly at night, which causes its pleasing aroma. Sometimes only one of many flowers will open on any given evening; uncommonly, the flower may never open again. Not to worry as the plant that reaches heights between 1 and 5 feet is filled with many blossoms. The lance-shaped leaves and 2-inch flowers weave around the sturdy, baton-like plant structure.
Hollyhock (Alcea rosea) resembles 6-foot long vertical vines composed of columns of rich green leaves and colourful blossoms. The flowers, which are approximately 3 inches across, may come in red, pink, purple, white, yellow and black. Hollyhocks attract many insects -- both pollinators and pests. Despite the fact that problem insects may munch on hollyhock leaves, this biennial is relatively easy to grow. If you use natural or chemical pest deterrents early on, you should eliminate the pests effectively.