- This is Mark Isselhardt,
Maple Specialist
with University of Vermont Extension.
This is a Vermont Maple Minute.
Why does sap flow from maple trees?
Throughout the maple region
there are several weeks of alternating
freeze and thaw temperatures each spring.
This weather provides the right conditions
for sap flow in maple.
Unlike most trees,
maples have tiny, air-filled cells in their wood.
Freezing causes ice to form inside these cells.
As this frost thickens,
a suction is created
which pulls water from the soil
into the tree.
At the same time,
the gas bubbles in the cells are compressed.
When weather warms,
the frost melts and the gas bubbles expand
causing pressure to form in the tree.
This pressure pushes sap out of the tap holes
drilled by maple producers.
In order for the sap to keep flowing,
another freeze-thaw cycle
must follow within a day or two,
or if producers have vacuum
attached to the taphole,
sap will flow for many more days.
This has been a Vermont Maple Minute.
I am Mark Isselhardt, Maple Specialist
with University of Vermont Extension.