Deb Babcock: They’re not dead, just dormant
January 31, 2011
Steamboat Springs — Now that most of our gardens are asleep under a blanket of snow, you might wonder how your plants make it through a long, cold Steamboat Springs winter. Especially one as cold as this year's has been.
Even though it seems that winter comes fast here — fall one day, winter the next — our plants know winter is coming through a process called vernalization, or dormancy. Your plant's shutting-down process is triggered by the increasingly fewer hours of daylight as the sun rises lower in the sky. Then when temperatures drop to freezing, the plants go into the final stage of shutting down for winter.
Different plants require different hours of daylight to begin the process of dormancy, and this often depends upon where the plant originated. However, more often we see plants that were specifically bred to handle different periods of dormancy. For instance, farmers can find cereal crops that require shorter periods of dormancy, allowing for the harvest of multiple crops in a season. Some mild-climate vegetables and flowering plants have been bred for greater cold hardiness so that we now can treat them as perennials in our Zone 4 gardens rather than as annuals.
That's also why plants rated for USDA hardiness zones higher than 4 often cannot survive here. They are unable to acclimate to our shorter days and lower temperatures.
Dormancy is a mechanism that helps a plant survive in a particular environment. Dormancy regulates when a plant should begin growing so that conditions are the most favorable for its little seedlings.
As day length shortens, plants begin storing nutrients for the winter in their roots, bulbs, and stems or trunk, in the case of woody plants.
When a plant completes the process toward dormancy, it simply moves to a period of inactivity. It transitions from being cold-sensitive, where it still is slowly growing, to cold-insensitive, where it stops growing and begins a period of rest. Some plants such as tomatoes, potatoes and southern climate flowering bulbs are unable to make this transition and will die if they freeze. The bulbs and potatoes need to be dug up and stored in a cool location until spring.
Other plants, such as many of our early spring blooming bulbs, pop up at the first sign of spring and can handle the inevitable spring snowstorm or frosty temperatures.
This important process of dormancy is one of the main reasons we recommend that gardeners stop fertilizing plants toward the end of summer. This and heavy watering could cause the plant to continue growing and not prepare itself for winter. If that happens, the plant might not have stored enough energy to survive.
To help your plants through winter, we also recommend mulching the soil around their roots to protect the root system from extreme cold. If you didn't get a chance to put down some wood chips or shredded bark, don't worry. Snow is an excellent mulch.
Deb Babcock is a master gardener through the CSU Extension Routt County. Call 970-879-0825 with questions.