Tree Saps expand the range, potential of forest farming


The following article is part excerpt from the book, part from a previous article on tree saps.

Tree Saps: Maple, Birch, Walnut, and Sycamore

One of the oldest forms of forest farming comes in the tapping of tree sap for delicious and nutritious products that arrive as the seasons change (thaw) from winter to spring. By far, the most common tree that is tapped in the northeast US is sugar maple, though there are several other trees that warrant attention, depending on the location of a forest farming operation. (See the article: 22 trees you can tap for sap)

Tree saps have long been viewed as a spring tonic by many cultures around the globe. Tree saps are loaded with minerals, nutrients, enzymes, antioxidants, phenolic compounds, and more. Worldwide, there have actually been three International Symposiums on Tree Sap Utilization, (1995, 2000, and 2005) where scientists from Japan, Korea, Russia, and Europe discussed the use of tree sap as an end product – mostly birch.

In Korea specifically, there is a long history of sap consumption and most comes from the Acer mono, a maple which is called gorosoe, meaning “the tree that is good for the bones” in Korean. This is likely due to the high mineral content in sap, most notably calcium, magnesium, and potassium. There are even places in Korea where people can take weekend retreats, visiting the mountains and consuming as much as 5 gallons of sap per day while sitting on heated floors with conditions similar to a sauna. The idea is to detox the bad stuff and unclog the body from a long winter. In Korean markets, Maple Sap usually sells for $5 – 10/gallon. (See this 2009 New York Times article on the topic)

While much of the medicinal benefits of sap around the world have focused on birch, several studies from Korea have cited the potential benefits of maple sap consumption in lab settings for treating osteoporosis, hypertension, and even curing hangovers. Most analysis has been done on the basic content of the maple sap, which has over 50 vitamins and minerals, and also a number of probiotics similar to those found in yogurts and other dairy products. More research would be useful, but it’s hard to argue against the idea of drinking sap as a healthy and good option for the springtime; after all, it is water filtered in a tree and loaded with a bunch of nutritional compounds. It may well be the cleanest water some people will ever be able to drink.

Picture of trees being tapping in Ithaca, from the History Center

Picture of trees being tapping in Ithaca, from the History Center

The process of collecting and boiling sap has barely changed over time. Innovations have mainly come in how sap is moved from tree to the fire and how quickly the boil is conducted. But the main process is both simple and timeless. Native American’s used sharpened stones and later hatchets, hacking a “V” into the trunk of the tree and collecting sap in a wooden trough. Sap was boiled by cooking rocks in a hot fire then placing them into the sap, constantly replacing rocks throughout the night. The natives also relied more heavily on letting sap freeze, which naturally separates water from sugar. The remaining liquid was then boiled off, but took a lot less time  than boiling alone. Some sugarmakers still take advantage of this freeze/boil strategy today.

Maple (Acer spp)

As implied by the name, the most often used tree for sugaring is the Sugar Maple (Acer saccharum ), though any of the maples can be tapped. In the Pacific Northwest, people are starting to more commonly tap the big leaf maple (Acer macrophyllum). These trees all produce copious amounts of sap as the days begin their freeze-thaw cycling, usually for 6 – 8 weeks in the months of February, March, and April. Sap flows up from the roots of the trees, awakening dormant buds and pushing forth flowers and eventually leaves that will be the solar array for the trees and the forest.

The sap of Maple is wonderfully delicious, crisp and fresh, loaded most notably with significant levels of calcium. 40 gallons of sap can be boiled to make one gallon of syrup. In a given season, a healthy tree can be expected to produce about 10 gallons of sap.

Walnut  (Juglans spp.)

Black Walnut syrup needs extra filtering.

Black Walnut syrup needs extra filtering.

Walnut trees are wonderful nut producers and also provide potential high value wood products. If trees are not candidates for the latter, then tapping in additional to nut harvest can be a nice combination of yields for the forest farmer. The tapping of walnut also opens up the possibility of sugaring for forest farmers in warmer temperate climates found in the Southern US and parts of the Midwest as well.

Walnut trees have a similar sap-to-syrup ratio as maple syrup, but sap yields from trees appear to be lower (1/2 to 1/3 less as compared to maple). Walnut sap flows in response to the free/thaw dynamics similar of maple, so often the need to boil is concurrent with maple syrup. An added challenge is that walnut sap contains a pectin-like substance which will cause syrup to harden if not filters multiple times through the boiling process.

On its own, walnut syrup is quite similar to maple syrup infused with the nutty taste one might expect from it. The sap can be quite astringent but also contains this nutty flavor, and some trees produce delicious sap. Researchers from Kansas State University recently experimented with producing black walnut syrup and then did some consumer research on preferences for black walnut vs. maple syrup. They found no significant differences on the likability scale between these two syrups and concluded that black walnut syrup could develop as a niche market in the Midwest.

Birch (Betula spp.)

Those who already tap Maples may want to consider also tapping birch trees should they be fortunate enough to have a stand in their woods. Birch sap doesn’t usually begin flowing until the end of maple season, and since the same equipment is used maple producers could simply switch over and continue to make syrup. Yet, of course there is a catch; while a gallon of finished maple syrup take 40 – 50 gallons of sap, it’s more like 100 -200 for birch, due to it having a much lower sugar content (1-1.5%). This is one of the reasons its use as a sap is so popular worldwide.

While maple and black walnut saps run in response to dramatic changes in temperature dynamics (also know as stem pressure), birch sap operates off root pressure, which requires that temperatures stay above freezing day and night. Thus, since collection and boiling equipment is the same, birch could be seen as a form of season extension for sugarmakers.

The extra time and expense can pay off, however, as birch syrup is sold for $350 – $400 a gallon (Maple is $45 – 60 for a gallon), and with demand far outstripping supply, it’s a farmers market. Most of the available birch syrup comes from Canada and Alaska, where birch forests are more common. But many northern states have the potential to “tap” into their birches as a source of syrup.

Birch syrup is not for pancakes. It’s fruity, spicy, and sometimes remnant of molasses or licorice in flavor. The primary sugar in birch syrup is fructose, versus in maple, which contains mostly sucrose. The former is touted to be an easier sugar to digest and also contains the lowest glycemic index of all sugars, which makes it the most suitable sugar for use by diabetics. The syrup boasts a high vitamin C content and good amounts of potassium, manganese, thiamin, and calcium. (Cornell is actively doing research with birch)

Sycamore (Platanus occidentalis)

Range of Sycamore. (Source: USDA)

Range of Sycamore. (Source: USDA)

Sycamores can be found growing wild in all states east of the Great Plains, except for Minnesota. The tree is very easy to spot in winter, even at a distance. These wonderful, fast growing trees are happiest in riparian zones and wetter places on the landscape. Few people tap this tree though the sap is quite good. Its quality and sap-to-syrup ratio make this a better candidate for sap – it take about 50 gallons of sap to more a quart of syrup, similar to birch.

The addition of sycamore to this list offers many more locations the opportunity to tap a tree for sap, notably the southeast, midwest, and even portions of eastern texas. Another tree in the same family, Sweet Gum, can also apparently be tapped, though this author has no experience with this.


Tapping correctly is the most important to take extra care and detail with, as tapping is essentially wounding the tree, and the goal is to create a “clean” wound that will heal quickly after the tap is removed. It is worth purchasing a special tapping drill bit from a maple supplier, as it will last forever and it is specially engineered to leave a cleaner hole, critical to helping the wound heal itself. Tapping can be done anytime from early to late February (at least in Upstate NY) up through the end of the season in late March to even mid-April some years. The key is to avoid leaving taps in longer than six to eight weeks; otherwise the tree will naturally heal itself around the tap hole and the tap will be almost impossible to remove. Taps should be removed as soon as trees break bud, if not sooner.

To select a spot for tapping, first examine the entire tree. Is the crown complete, and does is appear healthy? Avoid tapping areas that appear diseased or damaged. If the tree has been tapped in previous years tap the opposite side from the most recent hole. No trees smaller than 10” should be tapped.

proper position of spout

proper position of spout

Drill with a high-speed cordless drill about 1.5” into the tree. Take extra attention to keep the drill straight in and out of the tree, to avoid an “oval” hole.  The goal is to get through the sapwood and slightly into the hardwood center of the tree. Insert the tap and hammer lightly until the tap is snug in the hole. Hammering too hard will result in split wood, which takes longer to heal.

Keeping it fresh

If you are interested in collecting and enjoying sap, its important to note that while sap is essentially sterile when inside the tree, it can quickly become contaminated. The choice of container for collection is thus very important. Maple buckets and jugs (a milk jug can make a great collection vessel) should be thoroughly cleaned before use. The best sap runs during the beginning and middle of the season, but as the temperature warms toward the end of March and into April it’s best to stop drinking it straight. Sap can be stored in the fridge (or outside if below freezing) for several days and should generally be treated like milk; best consumed within one week of it coming from the tree.
And while some of the good bacteria may be killed, to be extra safe some choose to boil the sap to effectively pasteurize it and render it completely safe. Sap can be drank straight from the tree of course, but can also be used to make a wonderful carbonated beverage with a home soda-maker. Simply replace the water with sap, adding as much or as little carbonation as you’d like. It can also be utilized for cooking in soup, stews, and other recipes that call for water. It also makes a wonderful base for brewing beers.

The straight consumption of sap is an excellent option for people who want to tap some trees but aren’t interested in the time, labor, and fuel to boil it into syrup. It offers an opportunity to harvest the fruits of a long winter and connect to the cycles of the season. While the entire process of making syrup takes considerable energy, sap is just the opposite – it is really simple and takes very little time to tap, collect, and consume sap in a variety of ways. In addition to landowners tapping trees for their own sap, we will be seeing more and more commercial availability of sap, sap sodas, and other products, as the tree sap industry continues to grow.

collecting sap.

Elizabeth collecting sap at Wellspring Forest Farm.