Watering Trees And Shrubs

Watering Trees And Shrubs

People often ask how to water a tree, when and how much. Is there a regular schedule that one should follow to water trees and most plants in general? The answer is simple, check the soil regularly and water when dry. Do not overwater as this prevents the roots from having access to oxygen, low oxygen levels to the roots will encourage them to rot. Trees take up water through the roots by osmosis and transpirational pull which means water evaporating from the leaves is pulled up from the roots. Trees transpire throughout the day and mostly respire during the night, this is important to know when deciding what time of day to water.
The best time to water is during the morning so that the tree can have access to water when it needs it. Avoid watering during the hottest period of the day as much of your water will be wasted by evaporation from the ground. How much to water is also an important factor, ideally the best way to water your trees is to apply a large volume of water over a long time period, water heavily and less frequently.
A soaker hose is perfect for watering trees because it allows for water to be applied slowly so that the soil can be watered to its full capacity instead of just watering the surface with a sprinkler. Where you water should also be considered because you want the water to be where the feeder roots are. Let’s consider roots for a moment, roots can grow out as far as a tree is tall so you need to water where the fine roots are.
Think of a tree like a petroleum industry, fine roots far from the refinery tap water wells, think of the larger roots closer to the trunk as pipelines to transport the water from the wells all the way up the trunk to the leaves which act as refineries. When you water close to the trunk think of it as pouring oil over a pipeline instead of having it flow through the pipeline. Moisture on the trunk can also cause damage and rotting on the bark of trees growing in a dry climate like our own. You can also follow the dripline example for watering most trees, water at and past the dripline to make the most of your watering efforts.
One exception for watering at the dripline would be columnar trees, I would water these trees wherever they cast shade (the shadeline) as this is where the roots would most likely be found considering the trees height. If a mature columnar tree had all of its roots only within the dripline it would surely fall over. Mature trees need significantly more water than young trees. Remember leaves pull water, more leaves/refineries means that more water is required for the system to work at capacity.
What about watering dormant trees and evergreens during the dormant period of the year should we? Yes if soil conditions are dry then the soil should be kept moist to keep the roots healthy and make water available for when the tree needs it. Watering during dormancy also helps keep a healthy root environment by creating beneficial conditions for microbial activity that promotes healthy soil and root development.
Most importantly is that you water your trees because it’s probably the most important resource that you have at your disposal to keep a healthy tree.


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