Watering Trees and Shrubs the Right Way

watering trees and shrubs

By Erin Marissa Russell

Many of the approaches to watering plants in general apply to trees and shrubs. However, there are some things you can do to improve the health of your trees and shrubs in particular. We’ve listed some of these tips in this article.

Tips for Watering Recently Planted Trees and Shrubs

While trees and shrubs aren’t yet established in their location, they need more water than they will once they’re more mature. For the first one or two weeks after planting new saplings, water them each day. For the third to 12th week after being planted, decrease your watering schedule to every two or three days. After that point, your recently planted trees will need water each week until their roots are well established. (Roots are “established” when they spread out just as wide as the tree canopy.)

  • Make sure that the area surrounding your recently planted trees and shrubs is clear of weeds. While all plants will suffer from weeds siphoning off their water supply when they are new in a location, other varieties of plants are less likely to be situated in an area where weeds already exist.
  • Water your recently planted trees deeply enough to make the soil moist to a depth of four to eight inches. You can test how deep the water you give new shrubs or trees is penetrating by digging four to eight inches deep near the area where these plants are growing.
  • Try watering at different speeds, delivering the moisture more slowly and more quickly, and observe carefully so you can tell how much water is being absorbed by the soil versus how much is running off and never reaching recently planted trees and shrubs. The appropriate speed for getting water to new trees and shrubs will vary based on the type of soil you have. Use the speed that results in the most water being absorbed in your test.

General Tips for Watering Trees and Shrubs

Trees and shrubs don’t stop needing water from the gardener once they’re well established, although their needs do reduce as they get used to their environment. Here are some tips for watering trees and shrubs in general, not only when they’re new in their location. A tree’s roots can be permanently damaged by a temporary drought that causes the soil around the root zone to dry out. The stress involved with surviving a period of drought also makes trees more susceptible to plant diseases, infestation by insects, and other types of damage, so it’s important for the long-term health of your trees that they remain well hydrated.

  • Despite the fact that plants can only take in water through their root systems, sometimes gardeners water from above, letting the moisture splash on the trunks and foliage of trees and shrubs. Hydration that lands on trunks, branches, or leaves can’t be absorbed by the tree and will stay where it lands until it evaporates on its own. During that time, the water may contribute to overly wet conditions that lead to fungal diseases or other plant problems, or it may become heated up by the sun and lead to sunscald, burning the tissues of the leaves. The best thing to do is to target the water you give trees and shrubs at the base of the plant, moistening the entire area of the root zone. The area you should be aiming for is from the trunk of the tree or shrub to the outside edge of the drip line, which is where the branches end. This way, trees and shrubs can put all of the water you give them to use. 
  • Because the roots of your trees and shrubs can extend so far into the soil, you can’t simply do a visual examination to determine how wet the ground is, and the soil test that works for plants consisting of sticking a finger into the ground won’t translate as well to your trees and shrubs. You could use a spade to dig deeper into the ground, but there’s an easier way to monitor how much moisture the roots of your trees have access to. Consider investing in a soil probe or soil moisture meter that can give you an accurate picture of the water level underground. 
  • Giving trees and shrubs just a little bit of water on a frequent basis isn’t nearly as beneficial for them as deeper waterings given less frequently. For best results, water your trees and shrubs deeply and slowly once per week or so. There are a few approaches you can take to accomplish this. 
  • Consider placing your garden hose in different spots at the edge of the tree’s drip line (the farthest point its branches extend to and letting it run for a while before moving it to a new spot. 
  • You can use a sprinkler system similarly to the way we describe using a garden hose above. To measure how much water you’ve given a tree or shrub, place a container with straight sides near to the sprinkler as it runs, letting the tree fill up on water until the container has one or two inches of water inside. Giving your tree as much water as it would get from one or two inches of rain means the water will have dripped down into the soil about six inches, which is where the fine roots that take in water are located. 
  • You can also rely on watering bags purchased online or from a local nursery or garden center to give your trees and shrubs the hydration they need. Use watering bags by filling them up with water and situating them either around the trunk of your trees and shrubs or near the trunk on the ground. The watering bags will deliver moisture to the soil that the root zone lies underneath. One benefit of using watering bags to give moisture to your trees and shrubs is that you’ll know they are receiving the same amount of water every time, ensuring consistency in their watering routine. Watering bags are a particularly good option for younger trees or recently transplanted trees and shrubs, which tend to need a bit of extra attention. 
  • The plants that line the street need water just as much as those in the interior of your yard, so don’t forget any of the trees and shrubs along the road or parkway when you’re dispensing water. 
  • Summertime isn’t the only time your trees and shrubs need water. As plants prepare for the long dormancy of winter, it becomes especially important for them to get plenty of moisture. That means you should keep watering your trees and shrubs for as long as you’re able to until freezing weather arrives.
  • Grasses and other plants growing underneath your trees will actually compete with your trees or shrubs for water and nutrients in an unhealthy way. When there isn’t enough moisture to go around, as is possible during the heat of summer, trees that lose out on water and nutrients to the plants growing under them will show it in symptoms such as smaller fruits, reduced bud development, or lower overall growth. Removing the grass or other plants that grow under your trees allows the root system to distribute itself more evenly, increases the number of roots overall, and permits the tree to call on a larger amount of soil to house its root system. Trees with a larger root system that makes use of a higher volume of soil are able to use water and fertilizer more effectively and efficiently.

It’s easy to overlook trees and shrubs when we’re watering the plants in our garden simply because there’s a unspoken belief that once these plants are well established, they’ll get all the water they need from Mother Nature. However, especially in warm regions or when the weather is hot and dry, this isn’t always the case. The information in this article should have given you everything you need to know to make sure the trees and shrubs in your garden stay hydrated, whether they’re recently transplanted or have been at their posts for some time.

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