You should be watering trees properly in autumn as a preventive measure to protect them from winter damage. The winter damage that trees sustain often stems from their inability to draw water from the frozen earth. Watering trees properly in autumn can minimize this winter damage.
Unfortunately, it's not as easy as simply watering trees a lot. Your tree watering also has to come at the right time in autumn. Watering at the wrong time can actually do your trees harm! The following is the proper regimen for watering trees in autumn:
- Stop watering trees, both evergreen and deciduous, throughout early autumn, until the time when the leaves of the deciduous trees fall. This will allow both evergreen and deciduous trees to enter a transitional phase, not unlike the "hardening off" undergone by nursery plants in spring. What you're trying to avoid here is causing spurts of new growth that won't be winter-hardy.
- In late autumn, after the deciduous trees have dropped their leaves, give both evergreen and deciduous trees a deep watering. This should be done before the ground freezes.
- Water evergreen trees during "January thaw" and other warm periods that pop up unexpectedly in winter.
Following this tree watering regimen is especially important for the evergreen trees, which, although their growth slows down, do not enjoy quite the same period of dormancy that helps protect deciduous trees. Evergreen trees keep their foliage during the winter months. That foliage is continually giving off moisture throughout the winter -- moisture that is not readily replenished in the virtual desert conditions discussed above. You can promote the health of your evergreen trees by allowing them to enter the winter season well-watered.
