Posted by mary luther on March 20, 2006

Q: Does the roots of trees grower deeper in winter to allow them to continue to obtain water?

A: No, the roots don't grow deeper in winter (I'm talking about temperate North America) although in some trees (conifers especially) there is a fall spurt of root growth. Although the surface of the soil may be frozen hard in winter, as one digs deeper, the soil warms until it is no longer frozen and the roots here can absorb water. Deciduous trees really don't lose much/any water over the winter since they have no leaves for transpiration but the conifers do. Although transpiration is slowed in winter for the evergreens, it does occur.

If an area gets an especially hard freeze that goes deep into the ground, conifers that were planted the previous season are at risk with their shallow roots. These conifers may not have enough roots or deep enough roots to continue providing moisture and some or all of a tree will die. You may have seen newly planted trees in local yards that became really brownish orange in the winter - that's why. Thanks for an excellent question.

John Wiessinger ( March 21, 2006)