Watering your freshly cut Christmas tree right will pay off later

Sun., Dec. 5, 2010

Karen Herzog Milwaukee Journal Sentinel

Tree tips

• If you cut a tree at a farm, keep it fresh when you get it home by laying it on the ground out of the sun and wind until you are ready to put it in your house. Cover it to keep it cool and moist.

• When you’re ready to place it in a stand, cut one inch or more off the trunk. This will open the capillaries, which allow the tree to draw moisture up the trunk and into the needles.

• Check your stand twice daily – especially in the first week – and add water as necessary. An 8-foot tree can often “drink” a gallon of water per day.

• Choose the location of your tree carefully. Do not place it near a heat source such as a register, fireplace or window where direct sunlight hits it.

• Often, a tree obtained soon after its arrival on the retail lot will be very fresh because it was cut recently. Consumers should ask the retailer when he/she gets the trees: Are they delivered once at the beginning of the season, or does he/she obtain several shipments during the season?

• Do a freshness test on the trees. Green needles on fresh trees break crisply when bent sharply with the fingers, much like a fresh carrot. Pines have different indicators because of the fibrous nature of their needles compared to firs. The needles on fresh pines do not break, unless they are very dry.

• Look for other indicators of dryness or deterioration: excessive needle loss, discolored foliage, musty odor, needle pliability and wrinkled bark. A good rule-of-thumb is, when in doubt about the freshness of a tree, select another one. If none of the trees on the lot look fresh, go to another lot.

Source: Wisconsin Christmas Tree Producers Association

If you’re heading to a Christmas tree farm, heed the research of tree scientist Les Werner and his students:

Keep that fresh-cut fir or pine watered once you get it home, and you’ll be rewarded with fewer needles to sweep off the floor.

Werner for years thought that keeping water in the Christmas tree stand was pointless.

The University of Wisconsin-Stevens Point associate professor of forestry never watered his own family’s Christmas trees because he reasoned trees stop photosynthesizing when they’re cut from their root systems.

“For years, I asked plant physiologists around the country, ‘Do you water your Christmas tree?’ ” Werner says. “Most of them, like me, said they didn’t. But their wives would water the tree behind their back.”

So Werner and two students decided to document moisture loss in cut Christmas trees that were watered versus those that weren’t. A tree farm donated 54 fresh-cut trees for a four-week study.

Werner’s team set out to study whether loss of a root system, combined with an unnatural indoor environment, would severely limit a cut Christmas tree’s biological functions, including water uptake, photosynthesis and transpiration.

The research proved a direct correlation between needle retention and moisture content, Werner says. Needle moisture in unwatered trees diminishes significantly over time, while watered trees maintain needle moisture.

Based on the research, he advises consumers to buy as fresh a tree as they can – or to cut their own tree – if they don’t enjoy sweeping needles.

“Then make sure you give it plenty of water for at least the first week and a half, when it takes up the most water,” Werner says.

After about a week, the tree will respond to the cut on its trunk by excreting resin, which naturally seals the “wound.” Then it no longer takes up as much water.

Cutting a few inches off the trunk before putting it in the stand opens the capillaries to allow the tree to draw moisture up the trunk and into the needles, Werner says. The water level should be two to three inches above the cut.

For those who believe in adding sugar, aspirin or vodka to the tree water, none of those so-called additives will help, Werner says.

“I would love to come up with an additive that works,” he says. “Clean water still works the best.”