Watering a tree is not as straightforward as it seems. One of the biggest reasons that new trees or newly transplanted trees fail is because they are not properly watered.

If you water too much, it forces oxygen out of the soil and creates oxygen starvation of the roots. This causes root death and leads to the decline of the tree. One sign of this is yellowing of the foliage. This usually starts low and on the inside of the tree and moves to the outer leaves.

Here are some additional tips:

• Water infrequently but deeply  -- to at least 6 to 8 inches. Then allow the soil to dry out some between applications.
• Avoid frequent light watering, as this promotes the development of shallow root systems that are susceptible to winter injury and summer heat stress. Most tree roots are not very deep (within the upper 6 to 12 inches of soil), and deep roots will receive water if enough is applied to the soil surface.
• Avoid applying water directly to the trunk.
• Water with an open-end hose at a rate low enough to keep the water from running off.
• Water one hour per inch diameter of the tree. Tree roots extend away from the tree at least as far as the tree is tall, and in most cases much farther.
• Place the hose at or beyond the drip line for the most effective watering.
• Add mulch around the base of the tree to keep moisture in, improve water and air penetration and keep the soil temperature stable. Use wood chips, shredded bar, dried grass clipping or pine needles and cover the base 3-4 inches deep.