Watering trees. How much water?

[ChippersTreeSvc]

Does anyone if there is a rule of thumb for how much water established trees need depending on trunk size? I've read ISA BMP book but it only talks about newly planted trees.

 

[moonfarm]

I've never seen recommendations, but I think any one would be more based on square footage than trunk size. I've always heard plants need a half an inch of rain a week in the growing season, so it wouldn't be too hard to calculate water requirements based on square footage of canopy off of that.

Tim

 

[Tom Dunlap]

There is a good fact sheet at the top of this webpage:

Texas ISA fact sheet-Watering, tree care, etc.

 

[treemaninmo]

the easy way to tell if tree is adequately hydrated is to go below the mulch layer and grab a handful of soil if it clumps well its wet enough if it crumbles it needs more water

but as far as water needed for established trees i would say this: once trees are established and if they ARE a tree that is suited to grow in that zone , they will do well on their own, so just a little bit of added water will do wonders if that makes since

when i was watering lots of trees in the heat of the summer we had a gravity fed hose maybe flowing 7 gals a min and i would water each one for about 3-4 mins. and this was done once a wk

if your grass around the tree is GREENer then your tree is getting enough water

hope this helps

 

[mdvaden]

If I was rolling a water truck to some location, I'd probably try and guess how many gallons to bring, but the trees would still be watered sufficiently even if I had to make a second trip.

What I suggest to customers ... and actually do at home myself ... is to cut wood 1/2" dowels to about 12" long and sharpen the tip. Then push into the root ball. Maybe one in the fill soil too.

Then pull those out every day, two or whatever, to check. If the stick is dry, the soil is dry. If the stick's wood is damp, the soil is moist. If the wood is wet and gummy, the soil might be too wet, but at least it's not dry.

Water meters can malfunction, but the wood sticks do not.

Link: Watering Tips Page

Watering seems tricky for offering guidelines because there are not just variables, but the variables are often buried out of view.

 

[Frax]

I get asked this question a lot. And I can never answer it. The suggestions posted about testing are along the lines of what I usually suggest to the asker. Species of tree, soil condition, mulch, and drainage all heavily weigh in.

I think in situations of perfect drainage you can't overwater at all. But you might leach nutrients and waste water. Think hydroponics.

If drainage is poor, overwatering is a disaster for most tree species.

Checking is the only thing one can do. If that is not possible to do all the time, at least assess what the soil tends to do at that loc during rain free periods and come to a reasonable conclusion about how much water needs to be added based on what is learned by that effort. In essence, create your own guidelines for that location.

 

[ChippersTreeSvc]

Thanks for all the information guys.

 

[cerviarborist]

Ed Gilman has it pretty well boiled down in a a couple matrices with USDA zones on one axis, trunk diameter on another, and how long the tree will require to become established, as well as one with trunk diameter and an irrigation schedule for either survival, or vigor. His premise is that the amount of time you or your client can commit to watering in the establishing tree, will dictate the trunk diameter tree you can successfully establish.

I can't attach the file, but you can download the entire powerpoint file titled "Choosing suitable trees for Urban Environments: Site evaluation and Species Selection" at this link http://hort.ifas.ufl.edu/woody/powerpoints.shtml
Slides # 44 & 45 pretty much cover it, although the entire powerpoint gives a lot of points to ponder in evaluating a site prior to selecting a tree to plant.

Be sure to read the narrator notes beneath the slides to get all the detail.

 

[cerviarborist]

If properly sited, established trees shouldn't need additional water, except in cases of extreme drought. More trees die from the result of overwatering than under-watering.

 

[Blinky]

For the purposes of talking to a customer I use a general rule i picked up at an urban forestry conference. 8gals/inch of caliper/month if it's slow and allowed to soak in.

It's obviously more complex than that but if the customer wants a guideline it should be adequate and easy for them to use.

Personally i do the soil test, I just feel it and if there's enough moisture in it to clump, good to go, if it granulates, water it.