As we near the end of July in Kansas City, it would appear that Mother Nature has decided to test the patience and stamina of gardeners and landscape enthusiasts. Unrelenting heat for weeks on end and virtually nothing in the rain gauge have combined to turn the verdant spring showcase into a beige wasteland. Vegetable crops have become unproductive and are drying up; lawns are downright crispy, and only the sturdiest perennials are hanging on. Perhaps most disturbing, though, is the decline in our most valuable landscape asset—trees! Newly planted trees (those less than 18 months old) are rapidly losing leaves and are now exhibiting tissue dieback at the terminal points and periphery of the plants. If supplemental water is not given to these trees soon, they will die. Worst of all, though, is the fact that mature, established trees are now showing signs of great stress and beginning to decline. We at Greenleaf would like to offer some tips and information about proper watering and how you can reverse the effects of Mother Nature’s wrath.
Of all the “deadly watering sins”, procrastination may be the most heinous. If you see the trees and plants in your yard wilting or dropping leaves, attend to them quickly. Especially with new trees, waiting until the weekend or until you have a convenient day off to water may spell doom for the plant. Plants can reach a point of “no return” wherein tissue damage occurs and vascular channels in the plants are interrupted to the extent that they can no longer carry water to the leaves and stems and the plant simply dies. The second “deadly watering sin” is relying on an irrigation system to water newly installed plants. No matter how good and how well designed your system might be, it cannot be relied upon to safely water new landscapes. In a drought situation, newly installed trees, shrubs, and perennials need individual attention with water being applied directly to the root zone of the plant. Another common mistake we landscapers see is applying improper amounts of water. Consider this: a fully grown oak or maple tree can transpire (breathe out) over 100 gallons of water a day—even more when the temperature rises over 100° and hot winds blow. So, standing in your front yard with a hose in your hand for a few minutes is not likely to really do a large tree much good! While any supplemental moisture is a step in the right direction, to really benefit a mature tree, the homeowner needs to thoroughly saturate the ground under the canopy (a few feet outside the dripline to the trunk) of the tree using a sprinkler or soaker hose. If you water only a couple times a month, remember it will take thousands of gallons of water to replenish that plant!
While we landscapers like mulch in our planting beds, improper use of mulch can cause major problems in a drought situation. If landscape beds are mulched too heavily (more than 1”-2”), mulch can actually prevent water from reaching the soil underneath and hence starve root systems for water. It is a good idea for a homeowner to pull the mulch away from plants and check the soil underneath; if the soil is not moist, that mulch should be raked away, the plantings fully watered, and then the mulch replaced.
The million dollar question in the watering world, is of course, how much water do I put on my plants? Well, the answer to that question is a loaded one—the correct answer is “provide how much it needs”. Not much help, right? That’s because each situation and each type of plant is different. A general rule of thumb is to allow the plants to tell you when they need water—if they wilt or “flag”, water them. Newly planted perennials and shrubs, in extreme heat, may require water every day or every other day. As far as quantity of water goes, try to imagine how large of a container the plant was grown in, and “fill” that imaginary planter with water in the landscape. If it was a 5-gallon plant for example, apply enough water to fill that 5-gallon bucket—a hint, it probably takes about one minute with a hose flowing freely to fill that bucket and quench that plant’s thirst. This rule of thumb also holds true for smaller trees grown in containers, but for large, balled in burlap trees, watering becomes more difficult. Large trees have large planting holes that generally can hold a lot of water—and in our clay soils, that large amount of water will dissipate slowly, so overwatering can be a danger. To properly water a large tree, saturate the rootball and the surrounding area, and then hold off watering for about a week. Watch the tree carefully for signs of wilt in that time period, and increase the watering frequency if necessary; however, if you apply enough water each time, large trees should almost never need water more than twice a week. Remember, a large tree with a caliper of 2”-3” or more will require one hundred gallons or more to saturate the root system.
Finally, a few comments about how best to deliver water to a planting bed. While it is possible to water plants with a sprinkler or irrigation system during a drought, remember to check the soil carefully underneath the mulch to see if your system is penetrating and doing a good job. Our recent experience shows that it takes several hours with a sprinkler to provide enough water to a landscape bed. The best way to water in a drought, especially for newly planted plants, is to hand water following the guidelines above. While laborious, watering in this manner also allows you to inspect each plant to make sure it is surviving the heat and check for insect damage, disease problems, etc. While being out in the heat is no fun, spending time in the garden during stressful times will pay benefits for a beautiful garden in the future.
At Greenleaf, we really care about your landscape and we don’t want to see it damaged by the drought conditions and intense heat. If you have questions about your plants’ health or how to water in your particular situation, please call us. We’ll be glad to help; and if you’re unable to water or will be out of town and need assistance in watering, we can do that too—properly and thoroughly. Let us be your maintenance resource! Happy gardening! (And stay cool!)
Contributing editor: Don Archer, Don Archer Designs in partnership with Greenleaf Garden Services