WSU researcher on how to keep Christmas tree fresh

Christmas tree
PUYALLUP, Wash. – The lots are open and shoppers are already buying and putting up their Christmas trees. But what’s the secret to keeping a Christmas tree fresh through the holiday season?
Be sure to provide it with plenty of water, advises Washington State University plant pathologist and internationally recognized Christmas tree expert Gary Chastagner.
Gary Chastagner in his WSU Christmas tree research
plot in Puyallup, Wash.

“Most people don’t realize how much water a tree can take up once it’s indoors,” Chastagner says. “As a general rule, for each inch of stem diameter the tree will need a quart of water per day. So the average four-inch diameter tree needs at least a gallon of water a day.”

Chastagner points out that keeping your holiday tree well hydrated is about more than aesthetics; a dried out tree is a potential fire hazard.
Another tip is to skip the additives that supposedly help the cut tree take up water. Research has found that adding commercial additives, sugar, 7-Up, bleach or other home remedies to the water provides no benefit, according to Chastagner.
“Water alone is the single most important thing,” he says. “All that’s needed is a fresh cut that removes about a quarter inch of the base before putting it in the stand, and keeping the stand filled so that the water level never gets below the base of the tree.”
Additional tips from Chastagner for selecting and caring for your Christmas tree include:
  • When selecting a cut tree, tap the butt on the ground a couple of times to see if it loses fresh green needles. Expect some dead brown needles to fall from the inside of the tree, but if it is losing more than a few green needles, it’s already drying out and should be avoided. Chastagner suggests that if you test a few trees and they are all dropping green needles, move on to another tree lot.
  • Once you get the tree home, trim a quarter-inch thick disk off the butt (unless that was done for you when you bought the tree) and put the tree in water immediately. 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.
  • Try to find a tree stand with adequate water-holding capacity for your tree. 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 says the water capacity listed on a stand’s label or box can be misleading: “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.”
  • Check the water level in the stand a couple of times a day, especially in the first week the tree is displayed, and keep the reservoir topped off with fresh cold water.
  • Display your tree away from heat sources such as heat vents, fireplaces and direct sunlight, because they will speed up drying. Lowering the room temperature will slow the drying process and reduce water use.
Chastagner’s primary research emphasis is on identifying and developing Christmas tree varieties for the Northwest Christmas tree industry that grow well in the Northwest, are disease and pest resistant, and have superior needle retention. About one-third of the nearly 36 million Christmas trees harvested in the nation yearly are grown in western Washington and Oregon.