I've been thinking a lot about weather lately. I get super excited about weather, especially thunderstorms and snow. I've been checking the weather back home in Kentucky from here in Portugal where we are visiting Joana's family. Not just once or twice, but many times the daytime temperatures in Kentucky have been warmer than here in Portugal throughout January and February. Yesterday, it was over 70°F there. It is February 13 and friends from back in KY are posting photos of spring ephemerals in full flower. So it got me thinking about winter and the role that winter plays in a given ecosystem. Questions such as "What if winter stops happening?" or "What if winter comes in April instead of January?" have been heavy on my mind, accompanied by not a small amount of feelings of trepidation and suspense.
The subject of winter has been one of the more patience-demanding (and humorous, upon reflection) conversations that Joana and I have had in sharing thoughts of our home climates. This region of Portugal, Sintra, is hardiness zone 10 which essentially means temperatures never get below freezing. Right now (mid-February), oranges and avocados are in season. So I understand Joana when the conversation usually dead-ends with her saying "Nothing grows there in the winter." It's true, for now at least. Deciduous trees lose their leaves ("The trees look naked!") and plants, trees and some animals go dormant.
The function of dormancy is a survival-mechanism that plants in colder climates have that temporarily stops their metabolic cycles in order to conserve energy for better growing conditions. To enter and exit dormancy periods, plants depend on a number of signals from the natural environment, including hours of darkness, precipitation amounts and specific periods of time in which the temperature has to be within a certain range. Once plants enter dormancy in the fall, they start to keep track of the amount of time that the temperature is below 45°F but above 32°F (known as chilling hours) and will not break dormancy even if suitable growing conditions exist until they have their required amount of chilling hours, usually between 500-1500 hours in total depending on the species.
Dormancy is a remarkably efficient and clever way to survive winter temperatures. However, breaking dormancy too early in the spring/late-winter, as is happening now with the unseasonably warm weather in Kentucky, can be harmful to bud growth, meaning less fruit production and in worst-case scenarios, plants and trees dying because they've started their growth processes and lost their ability to deal with colder temperatures.
I imagine that plants are struggling in breaking their dormancy in Kentucky this year, with daytime temperatures frequently in the mid 60's and night-time temps falling to well below freezing. Furthermore, the amount of chilling hours this season is already at 860 hours, meaning many plants and trees have completed or are close to completing their chilling requirements, are getting signals to break dormancy (and are doing so) now in mid-February, and exposing themselves to serious risk of frost damage to buds and aerial parts.
We are taking heed of the signals that weather and climate are showing to us. It is essential to permaculture to observe and interact and then accept feedback. To date, Kentucky has not experienced as much warming as the rest of the country. However, this is expected to change and we are integrating our observations into the design of our land.