Condemned to the mulch pile
Vail CO, Colorado
It’s pretty ridiculous even to me, when I stop to think about it, but there are times when I hate to sell an evergreen plant to someone planning on putting it in a pot as an ornament for winter. More often than not, it’s a condemnation to the mulch pile for the tree or shrub. It is, after all is said, just a plant, but I know how much time and effort was involved in growing that plant to specimen status.
I have no problem with growing pines, firs, and spruces to be cut for Christmas trees. That’s kind of a preordained noble ending for the tree. Pulp a tree for paper, no problem. Pulp-wood is grown like wheat with a longer crop time.
Furthermore, I happen to like the look of evergreens displayed ornamentally in pots ” whether symmetrically bracketing a dooryard, or asymmetrically displayed. There is something about having a plant green and alive greeting all at an entranceway. It is warm and inviting, in addition to green and white being almost as powerful a color combination as black and white.
But life in a pot for an evergreen can be a sort of slow torturous road to the inevitable yawning maw of the wood chipper. So, in an effort to improve the lives of trees in pots, I have taken up the cause of caring for potted evergreens during winter. I am of the school that believes that if one understands the roots of affliction, one will cease to afflict roots.
Most evergreens began preparation for winter back in the middle of September. The needles sensed the shortening days and through changes in hormonal levels they ceased growing and began to become woodier ” laying in a store of carbohydrates, cell walls modifying, hardening off. With the first freeze, the plants began to move water out of the woodier parts of the tree, roots and all, furthering the hardening process.
This process makes room for plants to move water in and out of cells to prevent the cell walls from rupturing as ice crystals form. Were the water to remain inside the cell, the ice would expand beyond the limits of the cell walls ability to stretch. Water resting in the areas between cells allows this water to freeze and expand and reduces the damages to cell walls. Pretty slick, huh?
The process works great, too, if it all occurs at a snails pace. Plants do not respond well to rapid changes in their environment. At the pace of plant life, a warm sunny day in a dark-colored, clay heat sink, otherwise known as a pot, combined with a cold clear night make for one hectic day leaving a plant beyond coping.
You can cope well enough for two, so allow snow to pile up around a pot, or, be a sport, and pile some snow around the pot for the plant. And, despite the fact that it will probably disrupt the feng shui you’ve sought, try to keep potted outdoor plants in the shade during winter. Snow reflects 90 percent of the radiant energy it receives. A brown pot does just about the opposite. You’re not doing a plant a favor by allowing it to warm up during the day.
Unfortunately, because the tree is brown and the needles green, the tree does a tremendous job of absorbing radiant energy and remains active. It transpires on days that lack humidity, which here, in winter, is pretty much all the time. It transpires overtime on windy days and nights, which also occur pretty much all the time here in winter as well.
If you want to do a plant a favor, if you see the soil in the pot is thawed during winter, water it. Most of the time in winter the water surrounding and inside the roots of a tree is locked up tight like block ice, but the top of the tree continues business as usual when it comes to giving up moisture. Replacing water lost to the atmosphere will reduce the browning of the needles that occurs when the tree is active, but its roots are frozen.
If you want to be a true mensch, leave the snow that accumulates on the branches and needles. I know it covers the green, but, the beauty of snow covered trees is almost cliche, and the as the snow melts it makes water available to the little pores in the needles called stomates, which the tree can then use to stave off drying out.
Upon review, about the only thing I have said in this article of practical use is that all the trees need to survive winter is a good blanketing of snow. Sounds familiar. I’m ready.
Tom Glass writes a weekly garden column for the Vail Daily. E-mail comments or questions about this column to firstname.lastname@example.org.