Every tree is an individual, with its own unique environmental, soil and underground conditions. Even a few feet can make a substantial difference in overall requirements. Some adjustment of these guidelines may be necessary for each tree.
If a tree is already established and healthy, it should be able to thrive mostly on its own. However, severe weather conditions can cause health stress for trees just as it does people. If a tree already has some challenges, whether natural or human-inflicted, sometimes supplemental watering during a critical weather event can mean the difference between life or death. Proper supplemental watering is also important when attempting to revitalize a stressed or dying tree.
All trees, regardless of age or size, should be given supplemental water during unusually hot and/or dry stretches of weather at any time of year, but MOST IMPORTANTLY during the hottest months of June, July and August.
GENERAL WATERING PATTERN:
Tree root zones should get a deep soaking (up to 18” depth ideally), then be allowed to dry out. DRYING OUT IS IMPORTANT. If the roots stay constantly wet, they will rot and the tree will die.
Late evenings or early mornings are the best time to water trees and plants.
October – March: Water only if there is an unusual period of drought (a week or more without rain), and no soaking rain is eminent.
April – September: Evaluate your watering needs when the temperature reaches 90 F or higher for 2 or more days in a row, with no recent soaking rain and none is eminent.
***June – August: These are critical months to monitor the weather. If weather conditions are stressful for humans, they are stressful for trees.
The goal is to soak the ground up to roughly 18” depth, in a “donut” shape around the tree, roughly underneath the outer 1/2 of the tree canopy. Watering any closer to the trunk is generally not as effective.
1. Use a hose without a nozzle laid down anywhere in this “donut” zone. Allow it to run for 30 seconds, a minute, or more in each spot to achieve a good soaking, to approximately 18”. If you have no idea, just do the best you can, some water is better than none. However, note the necessity to let the ground dry out between waterings. Do not leave the hose to run in one spot for an extended time. Most of the time, 1-2 minutes is enough to achieve a good soaking given an average level of run-off.
2. Soaker hoses can also be used, placed around the tree in the donut zone (NOT near or against the trunk), and left on perhaps overnight for a thorough soaking, but don't forget to turn it off!
Sun exposure. What is the tree's sun exposure? If the tree is situated mostly in the shade, less watering may be required. If in full sun, more may be required.
Drainage. Poor drainage can also affect the timing and amounts of supplemental water needed.
Slopes. Slopes can cause water to run off before soaking into the ground. This should be accounted for in watering.
If you use mulch, which can benefit trees only IF applied properly, we recommend using only coarse hardwood chips or pine bark (for evergreens) of roughly 1-2” diameter. No more than a single layer of 1-2” depth is necessary, more than this could be harmful as it does not mimic a tree's natural environment. We recommend NOT using shredded mulch, as this is often applied too deep, and can abruptly cut off the natural exchange of water and oxygen between the air and soil, which tree roots depend heavily on. In addition, shredded mulch over time will develop a glazed-over surface,
which causes most rain water to run off and not reach the tree roots. And in addition to that, shredded mulch will soak up much of the water that is meant for the tree roots. So if you use shredded mulch, apply it sparingly, less than 1" thick.
DO NOT OVERWATER. This is worse for your new tree than no supplemental watering at all. If the roots stay constantly wet, they will rot and the tree will die.
DO NOT USE A SPRINKLER TO WATER TREES. 2 problems with this. The water is spread too thin, and is likely not to soak deep enough into the ground to reach all of the absorbing roots. This method also sprays water onto the tree trunk, which is not natural (does not mimic the tree's natural environment), and can lead to trunk decay and circulatory problems.
DO NOT WATER THE TREE TRUNK. Water should be applied primarily underneath the outer half of the limbs for an established tree – this is where the majority of the absorbing roots will be.