Thursday, May 22, 2008

How Do I Water My Trees?

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.


Aiyana said...

I set my irrigation system to one extra watering because of our very high temps and winds. I think the wind is worse for the trees than the high temps. My potted Eucalyptus kruseana looked like it had been freeze dried. All the leaves fell off and I thought it was a goner. I watered it anyway, and see new growth, so perhaps it will recover.

Mary Beth said...

How wise to double up with your irrigation system! And I think you're right about the winds - they can be brutal to plants. Does Phoenix get many high wind days? I hope your Eucalyptus recovers well!
Mary Beth

Meems said...

Very good post, Mary Beth, with great information.

We are under very strict water restrictions here because of the drought. Our irrigation system can only run once a week which is no where near enough. I am dragging hoses around watering by hand (which is allowed)like crazy. Fortunately all my trees are mature but I know for folks who have planted new ones the heat and the drought make it difficult.
Meems @Hoe&Shovel

Mary Beth said...

In my area, we try to encourage people to wait until October, November or December to plant trees. Our Urban Forester claims that research has shown that trees planted in the Fall outperform those planted the prior jSpring or Summer. Beginning to establish the root system before it becomes brutally hot is key! Recently I saw some pictures of sod given different amounts of water. The sod watered deeply grew roots a foot deep! (I need to go through my things and see if I can find that article - it was pretty eye-opening) Needless to say it is probably much more drought tolerant! Good luck with keeping your garden beautiful through your water restrictions!

Lavender and Vanilla Friends of the Gardens said...

Mary Beth, thank you for your comment. I had a look at the roses you suggested. They are very beautiful and I will buy them. You have always very good advise.