By Pat Dray
The Garden Spot
Pat Dray
All of our “woody” plants go into dormancy, or hibernation, as a way to survive the winter. Annual plants do not go into dormancy since they have evolved to survive the winter conditions in the form of a seed.
Just as those bears we’ve been seeing “bulk up” with calories prior to hibernation, so do plants. When plants are in their growth period (generally April through August) they are using the process of photosynthesis to turn carbon dioxide, water and some inorganic salts into carbohydrates which are then stored in the plant roots for winter survival. Just as the bears use their stored carbohydrates to survive over the winter, so do our plants. This process is most obvious in our deciduous trees as the green chlorophyll is moved out of the leaves, turning them the wonderful fall colors we love.
Dormancy is triggered by changes in the angle of the sun, length of daylight and temperatures. These changes induce the plant to release plant hormones to signal dormancy and cold tolerance. The carbohydrates that the plant stored during the growing season are now sent down to and used by the roots to survive the winter. The plant also starts to move water from inside the cells to outside its cells so that the cells don’t burst when frozen.
Pretty amazing, isn’t it?
When plants go dormant, they begin tracking “chilling units,” which are the hours of time spent above freezing. Plants that are native to a region will have different chilling needs so, for example, plants native to the South have shorter chilling requirements than do our natives. This indicates to the plant that it is time to “wake up” and start the growth period by using the remaining stored carbohydrates in the spring. This makes sense when you realize that in Connecticut we cycle through warm winter days (above freezing) periodically through the winter. If a single warm day made plants come out of dormancy, they would freeze when it became cold again.
The dormant period is a perfect time for you to take a close look at your shrubs and trees. It’s much easier to see the growth pattern when the leaves have fallen. Do you see any crossed or damaged branches? If so, get out your loppers and do some winter pruning. Where are the bare spots in your garden? What changes should you make in the spring?
This cycle of growth and rest is also a metaphor for the effect winter has on us. Do we dread winter, or do we see it as a period of rest and planning for our spring planting? I know that I’ll be spending my post-holiday winter days planning for new growth.
Best wishes for everyone for the new year, and happy gardening in 2023.
Pat Dray is a past president of the Garden Club of Orange and a master gardener.