Everyone knows that trees need plenty of water. However, understanding how much water and when can get tricky. Watering practices differ depending on the season and the type of trees you have. Soil conditions near the tree are essential when watering the trees and shrubs in your landscape. Since soil and climate vary, checking the soil around the tree is the best way to determine whether it needs more water. Too much water can be just as detrimental to the tree as not enough. Before watering a tree, dig into the soil around the trunk and check the moisture level. It is time to water if the soil is dry a few inches under the surface. If it is wet, recheck it in a few days to determine if it's ready for more water.
If a tree is thirsty or has too much water, it will not thrive. Unfortunately, both can have similar effects. Leaves may wilt or change color when the moisture level is not correct. The lower branches and leaves droop with too much water and may become yellow or brittle. Keep an eye on your tree; if there is wilting or leaves are changing color, check the soil around the trunk to determine if it needs water or has too much. When you first plant a new tree, it will need immediate watering. It would be best to soak the root ball thoroughly right after planting to help it form its root base; this should soak the ground around the tree, about 18 inches in diameter. This first watering is crucial to its survival.
Why does a tree need water? Trees rely on water for everything they do, such as photosynthesis, respiration, and transpiration. Water is one of the most crucial elements in plant health because it is required to put all our other elements into a form usable by the plant. Almost all essential elements in ionic forms dissolve in water, allowing them to move to stems, branches, and leaves for energy.
Transpiration is the process your plants use to move water from the soil to the top of the tree, and it's solar-powered! As you know, water is absorbed from the ground into the plant's roots. From there, transpiration pulls streams of water up into vein structures inside the tree's trunk, limbs, and leaves. Once it arrives at the leaves, the tree "sweats" the water out through the bottom of the leaves in small openings called stomata. Transpiration moves massive amounts of water, even fighting gravity, and costs the tree about 90% of its water. The tree uses the other 10% in the growth process of the tree.
Changes in the weather, or extreme weather, the soil, and even the angle of the land, can all affect how much water your plants will need and how often to water them. Loose soil, such as sand, must be watered more often. Harder soil types like clay will retain moisture for much longer and need more time to dry between watering. All soils will remain moist longer in cooler months than in the warmer summer months. If your plants live on a hill, you must pay attention to how much water the plant can use and how much falls off too quickly. Water areas like this more often with less water to ensure the plants get everything they need.
Finding the perfect watering routine for your yard will take trial and error. However, here are some tips to get you started. First, allow the soil to dry entirely by not watering for several days to a week. Next, water your landscape as you usually would. Once the watering is complete, dig holes large enough to fit your hand 9 inches below the surface near the tree's base and just past the tree's drip line. If the soil is moist to the bottom of the holes, then that is enough water. If not, fill the holes and add 30 minutes of watering. Then repeat the process with new holes until both holes are moist. This will be the right amount of water to give your yard each time. It's important not to over-water as well. If your soil becomes mudding and sloppy, you have overwatered. Over the next few days, check if your soil is still moist 6 to 9 inches below the ground surface every other day. The soil will feel cool and damp if the moisture level is still adequate. Repeat this step every other day. Take note of how long it took for the top 6 to 9 inches of soil to dry; this will give you a reasonable estimate of how many days to wait between watering.
Of course, the same process will still apply if you have or plan to install an irrigation system. With the irrigation system, however, you can track your water usage and set future watering times to match the correct amount. Modern irrigation systems can even be set per the current season to ensure you don't over or underwater. Hand watering your plants can be a rewarding experience. However, irrigation systems ensure you never forget to water your yard and keep everything healthy no matter how crazy life gets.
Whether you hand water or want to use an irrigation system, you should consult an arborist about watering your yard. A trained arborist can detect attributes of your yard that may require slight changes in watering habits. For example, an arborist may want to test your soil for compaction and to ensure it has the proper nutrients to support the plants and trees that are growing there. Then, they can lay out an annual watering plan and even set your irrigation up if you plan to use one.