Horticultural Dictionary - Biennial

A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year the plant grows leaves, stems, and roots (vegetative structures), then it enters a period of dormancy over the colder months. Usually the stem remains very short and the leaves are low to the ground, forming a rosette. Many biennials require a cold treatment, or vernalization, before they will flower. During the next spring or summer, the stem of the biennial plant elongates greatly, or "bolts". The plant then flowers, producing fruits and seeds before it finally dies.