Plants Prepare For Winter’s Chill

PLANTS PREPARE FOR WINTER’S CHILL
 November 22 & November 24

As a child growing up on the family farm on Big Island, I always found wheat kind of cool. I would relish the taste of it right out of the bin of the combine and would consume handfuls of it at a time. But what intrigued me the most was its ability, after been sown in the fall, to remain green well into winter. Wheat had to survive numerous stresses through the winter, but somehow over time managed to evolve adaptive mechanisms for it to pull through. Low temperature, without a snow covering to protect the slumbering plants below the surface could result in winter kill. Likewise, dips in the field where heavy fall rains would cause water to pool, would also result in a patchwork of brown and lifeless sections in the spring.

We never give plants, and how they make it through the winter, much thought. We just take for granted that a renewal takes place once the weather becomes warm enough to stimulate growth. Plants have some rather interesting ways to survive the winter blasts. Plant cells have a lot of water in them which can quickly destroy a plant should that water freeze. Many plants get around this by moving water out of their cells; others simply reduce the amount of water, while still others move the water into the spaces between the cells to minimize damage from ice crystals. Some actually produce a type of plant specific antifreeze. Ever notice how much better turnips taste after a frost? That’s because they convert starches in their cells to sugars, for their antifreeze properties.

Of course, other perennial plants simply abandon the lush growth above ground, and retreat to their roots during the winter months. Annuals die down completely, relying on their scattered seeds to repopulate the soil each spring. Through all this, it is the snow which equalizes the ground temperature so all this can happen with minimal damage to the growing system.

Most amazing are the trees, their tall, stark frames catching the abuse of winter with no means of protection at all. We have all seen trees crack open, and may have even heard it happening on a cold day. A severe temperature change between day and night can freeze the water contained in the trunk of the tree causing it to split open. It is often referred to as southwest injury since it is commonly found on that side of the tree where warm afternoon sun creates extremes between day and night temperatures. The phenomenon is also common in the bark of shrubs too when it becomes known as bark split. This coupled with damage from wind and ice storms, we have to wonder how some trees manage to survive winter at all.

Another stress trees must undergo during the winter is dessication, or winter drying. We have seen it in evergreens, clusters of needles showing up brown and lifeless in the spring. This takes place when water is leaving the evergreen faster than what it is being replaced. Not difficult to happen when you consider that water is difficult for the roots to extract from the frozen soil in winter, especially if a harsh winter freezes the ground well below the root level.

We know that trees shed their leaves in the fall to conserve water, thoughtfully sealing the ends of the stems to prevent any further water loss to the tree. The tree can now settle into dormancy, but will still require water to keep it alive. Some trees, namely beech, are able to retain their deadened leaves through winter, the new leaves in the spring literally pushing the old growth off ahead of them.

If the weather in the fall is dry to start with, trees don’t have much to look forward to in the winter. If such a tree is next to a house with white siding, the drying damage can be intensified since it is now receiving reflected light and warmth, increasing the drying process.

In the whole process of trees and other plants wintering, there will be losses. It’s all part of Nature – winning a few, and losing a few. But Nature is very resourceful. She does not like a void for it is contrary to the natural world and its processes. Empty spaces are quickly filled in by other more resourceful plants.

I guess that’s why we always had weeds in our fields of wheat.