Protect your evergreens this winter
Last year, for the first time in fifty plus years, I bought an artificial Christmas tree. This fall I planted a real one. I honored the old realtor’s and gardener’s axiom: “Location. Location. Location.” I had the soil tested and amended to the recommended acidic pH level. I factored in full sun, adequate moisture, and air movement. I didn’t take into consideration howling winter winds. As I was listening to the weather forecast of a big Halloween storm, I wondered how I would protect my poor little Christmas tree.
Fine leafed conifers, like spruce, pine or fir, and broad-leaf evergreens, like hollies or rhododendrons, slow their growth but never go fully dormant. Because they retain their foliage during the winter they lose moisture year round. Wind exacerbates the problem.
Evergreens are especially important to gardeners in Blair County. Sometimes they’re the only spot of color we see in the dreary landscape from November to April. The real danger comes when both the plant and the soil are frozen. If the traditional “January thaw” occurs, leaves can thaw and release their moisture. When the water in the ground is frozen, the plant can’t replenish its moisture because the water can’t move up through the plant. The plant can, and often does, dry out and die.
Evergreens have some interesting survival mechanisms. Rhododendron Carolinianum is hardy in Zone 6 where temperatures rarely go below minus 10 degrees Fahrenheit. Rhododendron has thick dark green leaves in summer and in winter its’ colors range from dark cyan to eggplant. As the temperature gets colder the color darkens and the leaves curl and droop. Researchers think it’s a natural process to protect the leaves from desiccation.
Gardeners who have no choice but to expose their prized evergreens to winter winds have developed ways to protect their plants. You’ve seen them. Labor intensive sanctuaries involving yards of burlap to wrap or erect screens on the windward side of the plants. What you won’t be able to see is sprays of antitranspirant, which form a colorless waxy barrier on an evergreen. They are thought to allow gases in and out, but retain water molecules. In a strange triumph of technology over the natural scheme of things, many commercial Christmas tree growers spray their trees after they’re cut, to help the needles retain their moisture and reduce needle drop.
When antitranspirants were first introduced, they were advertised as a tool to reduce water loss and increase the survival rate of landscape plants. But in 2015 Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor at Washington State University wrote a paper titled The Myth of Antitranspirants. She says antitranspirants clog the tiny stomata or leaf pores, and can cause an increase in internal leaf temperature that can cook some plants.
Before I read her paper, I might have leaned to the “Spray and Pray” side. Now I think I’ll make a quick trip to Surplus City to see if they have any burlap left.
Contact Teresa Futrick at firstname.lastname@example.org.