Champaign, IL - Ryan Pankau with the U of I Extension shares the story behind sugar maples.
Right now is the time for collection of sap from sugar maples (Acer sacccharum) to make maple syrup. This easy, do-it-yourself-type activity is a great way to get a sweet, edible product from the maple trees in your yard or forest.
In late winter and early spring, maple trees yield sap for those willing to collect it. This unique process only occurs during the dormant season when a temperatures at night are below freezing (ideally around 20⁰F) followed by daytime temperatures that rapidly warmup above freezing (ideally around 40⁰F). If temperatures do not fluctuate enough, the sap flow will cease.
When conditions are right, positive pressure builds up within the tree as it warms from overnight freezing temperatures to warmer, above-freezing temperatures in morning. The flow is initially quite rapid and declines as the day continues. Each night, pressure is built up within the tree as air bubbles in sap decrease in size and dissolve when froze, which creates suction that draws sap from the roots. When the sap warms in the morning, the compressed air bubbles that were locked in ice overnight thaw and expand. The expand air bubbles create positive pressure inside the tree stem that will force sap out of the trunk if a hole or wound is present. Sap flow slows in the afternoon as stem pressure declines due to evaporation of water through branch tissue, internal leaks and other causes.
In central Illinois, late February to mid March typically provides the optimal conditions for sap flow, although timing may vary slightly from year to year. Sap flow will stop when the buds begin to expand and leaf development starts.
If you are interested in collection maple sap to make syrup, you don’t need a lot of trees. A significant amount of syrup can be produced from just a few trees if you diligently collect sap on a daily basis. There are a variety of sap collections methods available with very good information online. The process of sap collection is easy, beginning with a “spline” which is inserted into a 5/16” hole in the tree. Sap freely flows out the spline during the daytime. A variety of receptacles can be used to collect the sap from the spline, from mild jugs and plastic bags to metal buckets. Do some research and experiment to find a collection system that works for you.
Once your sap is collected, it must be boiled down to remove water and concentrate sugars into a syrup. It takes roughly 40 gallons of sugar maple sap to make one gallon of syrup. This process can be a little tricky as there is an optimal temperature that must be reached to “finish” your syrup. You will certainly need a good thermometer to monitor the boiling temperature of your sap. As the water evaporates, and sugars concentrate, your sap will begin to boil at a higher temperature. The sap is finished when it boils at 219⁰F (or 7.5⁰ above the boiling temp of water to be exact). If your syrup does not reach that temperature, it will spoil over time. If you go over, it will crystalize in storage. As you boil down the volume of sap in a larger pot, it may be helpful to transfer it to a smaller pot in order to better control and monitor temperature.
Maple sap collection is a fun and easy process that the whole family can participate in with minimal investment in new equipment. The rewards from this process are definitly sweet!!