Big tree holds moisture well on long trip

Christmas Tree sent to U.S. Capitol used in WSU study

By Sue Vorenberg, Columbian features reporter



Keep your tree healthy

Gary Chastagner, head of WSU’s Plant Pathology Research Program, shared these tips to help your Christmas tree last longer this season:

Slice a fresh cut from the bottom of the trunk before placing the tree in its base.

Use one quart of water per one inch of stem diameter in your water reservoir.

Don’t use any additives in the water; plain water works best.

Make sure to check the water reservoir at least once a day to make sure it’s full.

In past studies using these methods, the university preserved a Douglas fir for a little over three weeks, a Noble fir for between six and eight weeks, and a Nordmann fir for about three months.

Washington State University has some helpful news for you the next time you want to ship an 88-foot-tall Christmas tree across the country: Big trees appear to hold moisture well on long voyages.

Gary Chastagner, head of the university's Plant Pathology Research Program, and Katie McKeever, a graduate student and researcher, set up several sensors on the U.S. Capitol Christmas Tree that traveled on a 25-day journey from the Colville National Forest to Washington, D.C., in November.

The goal was to see how larger trees held up

through the shipping process, which is important for the Christmas tree sectors in Washington and Oregon. The two states provide between 30 and 40 percent of all U.S. Christmas trees each year.

"Most of those trees are shipped out of this region on trucks, and they go to most of the states and to foreign countries," Chastagner said.

Moisture content is important because it determines the look and health of the tree once it's on display.

McKeever installed the sensors at several spots inside the tree's branches. On the journey those sensors "automatically measure temperature every 15 minutes, providing statistics about the ambient environment inside the tree canopy," she said.

When the giant Engelmann spruce left Washington state, about half of the weight of its samples were water. A reading of 100 percent moisture means the water content of the tree is about half, and the Capitol Christmas Tree was about 95 percent.

The tree passed through a southern route and, although covered with a panel-covered frame, was exposed to 80 degree temperatures in Texas and temperatures just below freezing in Utah.

Despite the long trip — it usually takes three or four days for large shipments of smaller trees — the Capitol Christmas Tree performed well, Chastagner said.

"The moisture content of the tree in Washington, D.C., had changed very little," Chastagner said. "There was some fluctuation in transit, but it was still above 90 percent on arrival."

Generally, the larger the tree trunk, the more water it stores, he added.

Smaller trees need more sprucing along the way, although they generally hold up well over the shorter travel spans needed for delivery, Chastagner said.

The Capitol Christmas Tree took a longer route as part of a promotional tour through several states.

"If you were a Christmas tree grower this is something you'd never think of doing," Chastagner said. "The data we collected from the large tree really reaffirms it for more traditional trees and larger trees that you can ship them and keep them healthy."

The researchers did a similar study on the 65-foot-tall Pacific silver fir chosen from Washington in 2006, which traveled across country on a more northern route, he said.

In 2006, the Forest Service opened the trailer a few times along the route and sprayed water on the branches to ensure it would stay moist. This year, the service used a special water bladder affixed to the base of the tree to keep the moisture in.

Commercial shippers of trees also often spray water on them during shipment to keep them hydrated, which works well, Chastagner said.

The study cost less than $500, and the funds came from private donations to his program, Chastagner said.

He also has some general advice for people who are putting up Christmas trees at home for the holiday season.

"The most effective way to maintain the freshness of a tree is to add one quart of water per inch of stem diameter into the base, and to make sure you have a big enough base," he said. "So if you have a four-inch stem, you need a gallon water reserve."

You also want to slice off a fresh cut from the bottom of the trunk before placing it to ensure that the tree can absorb moisture.

Additives to water in the base of a tree aren't particularly useful and can be a waste of money, Chastagner said.

"You want to use fresh water, have a fresh cut base, and check the stand once a day to make sure it's full," he said. "Most of the water goes in the first week or so. But it's amazing how long cut trees can be maintained in the home if you do that."

For more information about Christmas trees, visit the program's website at