What makes an ideal Christmas tree?
Most of us look for things like shape, fullness and good color, but Washington State University plant pathologist Gary Chastagner has some additional criteria.
“For me, the ideal Christmas tree is one that’s relatively easy to grow in this region, has natural resistance to disease and pests, and has high moisture and needle retention once it’s cut,” Chastagner said. “The big thing is moisture retention, not just for appearances but because that means a more fire resistant tree.”
From the WSU Puyallup Research and Extension Center Chastagner is leading an international search for superior Christmas trees, working with collaborators in three Scandinavian countries, two Canadian provinces and several states.
Some of the collaborating organizations clip branches from trees in their regions that exhibit the preferred traits and overnight ship them to Chastagner’s Puyallup lab. He hangs them in a controlled environment and observes how well each holds its needles and retains moisture. Branch samples from the same trees are being tested repeatedly over a three-year period.
Because of restrictions on shipping branches from Europe, Chastagner has traveled to Denmark and other countries to conduct his research.
Trees with the appropriate traits are elusive. For example, recent samples from 94 Canaan fir trees found only 3 trees that did not shed any needles, according to Chastagner.
Once trees with the desirable characteristics are identified, clippings from them can be grafted to trees in a seed orchard. The resulting trees become “mother” trees, providing seeds carrying the desirable traits for use by the more than 1,000 Christmas tree growers in the Pacific Northwest.
“We’re simply taking the natural good traits in these trees and
perpetuating them,” Chastagner said. “That gives our Northwest tree growers a competitive advantage.”
According to the Pacific Northwest Christmas Tree Association, 11.3 million Christmas trees are being harvested in Washington and Oregon for this holiday season with an estimated value of $211 million.
Ninety percent of Northwest-grown trees are sold out-of-state. Most of them being shipped to California. But the Association points out that Northwest Christmas trees also are popular in Japan, China, Hong Kong, the Philippines, Mexico, Guam and Puerto Rico, not to mention Hawaii and Alaska.
Once you’ve found your ideal Christmas tree, Chastagner has some tips to make sure it not only looks good through the holidays but also doesn’t dry out and become a fire hazard.
— When selecting a tree tap the butt on the ground a couple of times and watch to see if any of the fresh green needles fall off.
“You can expect some dead brown needles from the inside of the tree to fall off, but if a tree is losing more than a few green needles it’s already drying out and should be avoided,” Chastagner said. “If you test a few trees and they’re all dropping green needles you should probably move on to another tree lot.”
— Once you get the tree home, trim a quarter-inch thick disk off the butt (unless that’s been done for you at the lot when you bought the tree)and put the tree in water. Unless you mount the tree in its stand right away, trim another quarter inch before placing it in the stand. That ensures that the tree will be able to take up water.
— Always trim the butt with a cut perpendicular to the tree trunk. Cutting it at an angle or “whittling” the base of the tree to fit the stand seriously decreases the tree’s ability to take up water.
— Use a tree stand with adequate water-holding capacity for your tree. As a general rule, the stand should provide one quart of water for each inch of trunk diameter, or a gallon of water per day for a 4-inch diameter tree trunk.
Chastagner researched Christmas tree stands, and found that only six out of 22 stands tested provided adequate water-holding capacity for trees larger than 4 inches in diameter.
“The water capacity listed on the label or box can be misleading,” Chastagner said. “That’s the capacity of the reservoir when the stand is empty, and you need to allow for the amount of water that will be displaced when the tree trunk is put in the stand.”
— Display your tree away from heat sources such as heat vents, fireplaces and direct sunlight because they’ll speed up drying. Lowering the room temperature will slow the drying process and reduce water use.
— Providing an adequate supply of clean water every day is the best way to maintain freshness. Chastagner advises against using water additives whether they are commercial preservatives or old home remedies such as adding sugar, aspirin or bleach to the water.”Additives don’t work,” Chastagner said. “Adequate clean water does.”
— Monitor your tree for dryness through the holiday season. If the tree is dry, remove it from the house.