"We believe everyone who wants to have a real tree will find one," said Doug Hundley, the association's spokesman. "They may not have the size they want or they might have to buy a different kind (because) we have a tight market."
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Home improvement store chains, which typically set up tree sales operations in their parking lots or nurseries, are watching warily.
"We have not experienced any shortages or cost increases from our suppliers this year. However, with demand being so high, we encourage customers to buy now to ensure they get the size and type of tree they want," Lowe's spokesman Matt Michaels said in an e-mail.
Supply isn't the only issue. Diesel fuel prices averaged $2.84 a gallon on Monday, 46 cents more a gallon than a year ago, according to AAA. That means higher shipping costs for truckloads of trees.
"The cost of freight on the darn things is up quite a bit, because diesel is up," said Jayne Mitchell, who runs Tim Mitchell's Christmas Trees in Scottsdale and Gilbert, Ariz. "I was unpleasantly surprised."
Mitchell said she is charging about $4 more for its popular five- to seven-foot Noble Fir. Larger trees will see a bigger price increase.
Another reason for small harvests today is a decreasing number of growers, their ranks thinned during the recession.
"There were a lot of tree growers that went out of business," said Dee Clark, owner of C&G Nursery in Newland, N.C. "That leads to an overall shortage across the industry.
Today, the U.S. is home to close to 15,000 Christmas tree farms. States that produce the most are Oregon, North Carolina, Michigan, Pennsylvania, Wisconsin and Washington.
Last year, 27.4 million Christmas trees were sold, the association said. The most popular varieties were Noble and Fraser firs, and consumers reported spending an average of $74.70 for a tree.
Reporters Kaila White of the Arizona Republic and Dillon Davis of the Asheville (N.C.) Citizen-Times contributed to this report.
Follow USA TODAY reporter Zlati Meyer on Twitter: @ZlatiMeyer