One of our favorite seasons at the BELL is blackberry season. You may have heard about it from your neighbors. We have scores of families arriving to pick their own blackberries often with the kids clutching their Halloween baskets ready to be filled with healthy summer treats. Blackberries may be the most well known biennial plants to most gardeners and even non-gardeners.
One of the many ways plants are categorized such as deciduous vs. evergreen, shrub vs. vine, tree vs. shrub, sun-loving vs. shade loving is by their life cycle, annual, biennial, perennial. In plants the life cycle is the period of time it takes for the seed to germinate, the plant to grow vegetatively – leaves and stems, produce flowers and then the fertilized flowers produce new seeds.
An annual completes its life cycle in one growing season a growing season can be as little as one month or take almost an entire year. Corn is a great example of an annual. The seed is planted, the plant grows, produces a tassel at the top which is a cluster of male flowers; the silk and ear compose the female flower. The pollen is transferred from the tassel to the silks by the wind and only the dormant seed is left to be planted again in the next growing season.
By definition perennial plants live three years or more. Herbaceous (plants with no persistent woody stem above ground) perennials are plants that bloom year after year. Their tops die back to the ground each fall, but their crowns and root systems remain alive, though dormant, during winter. They regrow from those roots and crowns when conditions are right the following spring.
But what is a biennial? Basically, biennials in the garden are flowering plants that have a two-year biological cycle, they complete their life cycle over two growing seasons. Biennial plant growth begins with seeds that produce the root structure, stems and leaves during the first growing season. A short stem and low basal rosette of leaves remains through the winter months. During the biennial’s second season, the plant growth continues with the formation of flowers, fruit and seeds then the mother plant dies. Common biennial plants in the flower garden include foxgloves and Canterbury bells. But in the vegetable garden cabbage, kale, Brussels sprouts, carrots, and celery are also biennials! We usually harvest them after their first season of vegetative growth, so we never actually see the flowers.