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- This is Mark Isselhardt,

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Maple Specialist

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with University of Vermont Extension.

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This is a Vermont Maple Minute.

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Why does sap flow from maple trees?

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Throughout the maple region

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there are several weeks of alternating

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freeze and thaw temperatures each spring.

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This weather provides the right conditions

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for sap flow in maple.

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Unlike most trees,

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maples have tiny, air-filled
cells in their wood.

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Freezing causes ice to
form inside these cells.

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As this frost thickens,

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a suction is created

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which pulls water from the soil

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into the tree.

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At the same time,

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the gas bubbles in the
cells are compressed.

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When weather warms,

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the frost melts and the gas bubbles expand

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causing pressure to form in the tree.

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This pressure pushes
sap out of the tap holes

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drilled by maple producers.

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In order for the sap to keep flowing,

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another freeze-thaw cycle

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must follow within a day or two,

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or if producers have vacuum

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attached to the taphole,

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sap will flow for many more days.

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This has been a Vermont Maple Minute.

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I am Mark Isselhardt, Maple Specialist

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with University of Vermont Extension.