Watering Mature Landscape Trees

Question:

We have a forty-five-year-old Flowering Pear in the middle of what was once a lawn. We occasionally water it with "gray water" from the washing machine rinse cycle but it’s not looking so good. I’m wondering if it should be watered more often?    

Answer:

A  Flowering Pear tree is an ideal shade tree that thrives in turf areas but it’s not a drought tolerant tree even after a very wet winter. It requires more frequent watering than you’re giving it now.
  • You didn’t realize it but it started to show signs of stress last year when it when dormant very early like in August or September after the leaves turned a maroon color. You also might be seeing burnt foliage or die back at the top and/or sides of the tree. Fireblight also causes die back so you could have both of these problems. So, it’s very important to water this tree regularly to keep it healthy.
  • The water shouldn’t be applied to the trunk but around the tree’s drip line, as it probably has a fair amount of surface roots. I’d construct a six to eight-inch high watering basin around the tree that extends from the trunk to the drip line. When the temperatures are less than ninety degrees, I’d water every seven to ten days and more often when it’s warmer.
    • A three-inch layer of mulch is strongly recommended to help insulate the soil and conserve moisture. I’d fill the basin up two to three times, to begin with, to add back moisture to the soil.
    • Beside hand watering, you could also use a soaker hose. You need to apply eight inches of water per season once the rainy season ends through October. You’ll first need to calculate how long that will take with your soaker hose. To do that, you’ll need several inch deep tuna or cat food cans and place them under the soaker hose and turn on the water. You want to find out how long it takes to fill the cans up. For our example, let's say it’s two hours. So, we know it takes two hours to apply and inch of water and we need eight inches per season so that would be sixteen hours.  The nonrainy season is four months long, June through October, so you divide four months by sixteen inches and that gives you four inches of water per month or an inch per week.
    • You could simplify things by installing a water timer at the hose bid and attach your hose to it. It’s very similar to the one used to turn on and off indoor lights. The timer allows you to water from fifteen minutes to two hours. All you’ll need to do is manually set the timer to two hours and it will turn its self off.
  • You may not see a lot of difference this year as most of the damage has already occurred.

Note:

Trees beautify our surroundings, purify our air, acts as a sound barrier, and help us save energy with their shade. That being said, trees get little respect from their homeowners. The aesthetic value of a mature tree is a quantifiable number as it increases the property value as much as twenty percent. Also, your favorite garden center doesn’t have a supply of mature, forty-year-old, replacement trees. I'd suggest you keep the tree watered at all costs as you’re protecting an asset worth tens of thousand of dollars.