We're nearing summer and our temperatures are rising to Hotter than Hades levels. This time of year can really harm a landscape that is either new or in marginal to poor health. And with trees, we often don't see potential damage until it's been done.
High winds, high temperatures, and low humidity all contribute to an accelerated rate of transpiration (or the plant losing moisture through its leaves). So how best to replace that water lost? Well, it depends (don't you love that answer?)
It depends on how established your tree is and the type of soil it is planted in. Sandy soils need watering more often. Generally, you should water a newly planted tree deeply every three days - then twice a week - then weekly. Heavier clay soils will hang on to the moisture a bit longer so you'll begin by watering twice a week, then once a week then every other week as needed.
So just what is "as needed"? Dig under the tree's drip line a shovel depth. Feel the soil - if it's damp, wait to water. If it's dry, give your tree a nice long drink.
Place a slow running hose in the tree's bed and water deeply. I keep my tree beds clear of grass as far out as the drip line and form up a little border so the bed can fill with water. Turn your hose on so that the water runs at about the width of your pinky finger. Let it run for about one hour to fill the bed. This should be enough water to irrigate the tree to a depth of a foot or more.
Letting the soil dry out in between waterings is equally important! The bed will dry out from the top down. That means the roots will grow DEEP into the moist soil. Having your roots grow deep will make your tree more drought tolerant.
Many people think that their sprinkler system is going to water everything amply. If your system treats the lawn that same as the planting beds the same as the trees, your trees will need some supplemental irrigation the first couple of years.
Another wonderful thing you can do for your trees is to mulch the beds 2-4 inches deep. This will lower the ground temperature and retain moisture.
There is nothing that cleans the air or lowers the temperature as well as shade trees. You have invested alot of time and money on your landscape trees. Treat them well.