Why winter matters in the garden

Vernalization is a process that some plants undergo in response to prolonged exposure to cold temperatures, typically during the winter season. This process is important for the flowering and reproductive development of certain plant species. But why does vernalization matter for plants?

Flower Induction

Vernalization helps induce the transition from the vegetative to reproductive phase in plants. Many plants have a requirement for a certain period of cold temperature to initiate the flowering process. This adaptation allows the plant to synchronize its reproductive cycle with favorable growing conditions that follow winter.

Adaptation to Seasonal Changes

Vernalization is an adaptation to the seasonal changes in temperature. By requiring exposure to cold temperatures, plants ensure that they do not start flowering too early, which could be detrimental if frost or other harsh conditions persist.

Genetic Regulation

The vernalization process involves changes in gene expression that are triggered by cold temperatures. This genetic regulation plays a crucial role in controlling the timing of flowering. The exposure to cold is sensed by the plant, leading to modifications in gene activity that prepare the plant for the transition to the reproductive phase.

Enhanced Yield and Survival

Vernalization can contribute to increased yield and survival of certain crops. For example, winter wheat and winter barley varieties undergo vernalization, allowing them to establish roots and undergo some growth before winter sets in. This early growth gives these crops a head start when spring arrives, resulting in higher yields.

Environmental Adaptation

Plants that require vernalization are often adapted to specific environmental conditions, such as the length and severity of winter. This adaptation allows them to thrive in regions with distinct seasons.

Although vernalization is more commonly associated with flowering plants like grains, there are a few vegetables that also benefit from or require vernalization. Some varieties of cabbage, Brussels sprouts, bulbing onions, hardneck garlic and carrots require vernalization.

Most bedding plants do not require vernalization because they are annual, but a few biennial and perennial flowers benefit from vernalization for optimal flowering and seed production.

Pansies are often grown as annuals but are actually short-lived perennials. Some varieties of pansies benefit from vernalization. Sweet William is a biennial or short-lived perennial and may benefit from vernalization. Cold exposure in the first year can lead to better flowering in the second year. Hollyhocks are often biennials and can benefit from periods of cold weather. Foxgloves and bellflowers are also biennial or perennial and can benefit from vernalization.