For birch tappers, it is time to turn eye and spile to the trees.

Within the next two weeks, experienced birch sap collectors such as central Kenai Peninsula resident Charlie LaForge predict the sweet, crystal-clear liquid will begin flowing as regional vegetation prepares for budding.

“Definitely within the next week or so,” LaForge said. “We could possibly see sap sooner in southern locations where the ground is already thawed out, or the trees might still wait until the typical time in their cycle.”

Mid-April is when the ten-day to two-week long window opens annually for gathering birch sap, also called birch water, according to the Cooperative Extension Service’s Backyard Birch Tapping and Syrup Basics publication, written by Alaskans Julie Cascio and Valerie Barber.

The free document provides step-by-step instructions for tapping birch trees, and is available at the Soldotna office, or on the extension’s website.

Approximately two viable trees are needed per season for personal use, LaForge said. The best trees have mature trunks that are six to eight inches diameter, he said.

“It is pretty obvious when trees are making sap,” LaForge said. “You can test a tree by drilling small holes.”

Occasionally, one may break open a “gusher,” which means the liquid may ooze out at one drip per second, LaForge said. Others may produce a steady discharge every three seconds.

“Be sure to tap on the shady side,” LaForge advised.

The “spring tonic” is light and sweet and can be consumed straight from the tree once strained of insects and residue, LaForge said. It is a good activity to do with children because the sap “appeals to kids’ taste buds,” he said.

The sap more readily flows when there is snow on the ground, so the season may be short this year, Barber said. The ground water feeds the system and the watery sap carries the sugars that feed the limbs preparing to leaf out for spring.

Freezing the liquid is another option for extracting water from the sap to concentrate the product, Barber said.

Barber, who has experience tapping in Fairbanks and around Palmer, said birch sap can also be used in teas and boiled down for syrup. However, because the sugar content is so low, it takes 100 gallons of sap to make one gallon of syrup, she said.

In 2013, Kahiltna Birchworks collected nearly 180,000 gallons to produce 1,600 gallons of syrup, said co-owner Dulce Ben-East, who co-operates the company with husband Michael East. To the couple’s knowledge Birchworks, based in Talkeenta, is the largest producer of birch products in North America, “by quite a bit,” she said.

The business is going into its 26th harvest, Ben-East said. The company uses reverse osmosis to concentrate the liquid, which isn’t necessary to make good syrup, but drastically reduces the labor, she said.

Gourmet Garden Market and Deli carries Alaskan-made birch sap products, including birch caramels, also known as the “Kahiltna Climax,” Ben-East said.

Interest in birch products is picking up internationally, Ben-East said. Birchworks has shipped syrups as far as Italy, Finland and Denmark. Previously they had been sending supplies to Canada, but smaller operations are popping up, she said.

On the Kenai Peninsula, birch trees have also been utilized for medicinal purposes, said Bobbie Oskoloff, member of the Kenaitze Tribal Association’s Traditional Healing Committee and researcher of natural healing methods. The sap can be used to heal wounds and fight infections. The bark was used as chewing gum in the past, she said.

John Winters, a Forester for the Division of Forestry office in Soldotna, said birch tapping is permissible for personal use on forestry lands.

Tapping is also legal in the Kenai National Wildlife Refuge, said Chief of Visitors Services Matt Connor. He advises not leaving plugs or spiles in trees and choosing trees slightly off of main trails so the activity is minimally invasive to other visitors.

“You want the trees to be accessible,” LaForge said. “Hauling sap from the refuge can be quite an undertaking.”

Birches can be found around Nikiski, Soldotna, Kenai and Homer, LaForge said. To get started, a spile or food-grade hosing, bucket and drill bit are all that are required, he said.

Reach Kelly Sullivan at kelly.sullivan@peninsulaclarion.com.