For you AZ gardeners: Tree watering question! (Goodyear: 2013, vs)

[M.Unit]

So we have two Desert Museum Palo Verde's (15 gallon) planted in our front/side yard about 6-7 months ago when we purchased from the builder. They have 3-4 2GPH drip heads each.
Shortly after being planted there was that really huge storm and I know the trees got more than enough water that ran deep and probably supplied all the water needed for the rest of the winter! And I'm thankful for that as the landscapers forgot to connect our irrigation system to the water meter....we didnt realize it till middle/end of January when we noticed some of our flowering vines were struggling.

So once the landscapers connected our system, they programmed our trees for watering 35 minutes, twice a week. Our vines/shrubs for daily, 20 minutes.
Trees and shrubs and vines (all are desert adapted) were doing great through rest of winter and early spring. Palo Verdes were in full bloom...then mid April all of a sudden the Palo Verdes dropped all the blossoms and started to drop all their leaves, one more than the other. They both are still very green looking but the one is completely bare of leaves. A few weeks back I decided to up the watering to an hour, twice a week...seemed that one of them did put back on some leaves and blossoms (a little) but the other is still bare of all leaves (actually, it probably finished dropping all its leaves). From different gardening blogs it seems the palo verdes drop their leaves in response to drought?

After doing a ton of research online, it seems since the trees receive a total of 6-8GPH and considering our clay soil we would need to water at least 3 hours (split into two waterings, an hour apart) either once a week or twice depending on how hot the weather is. And for our vines/shrubs, they each have 2GPH emitters...water 1 hour once to twice a week, depending on heat. This is all for trees and plants being established which mine are considering they were planted 6-7 months ago.

Does this watering schedule seem acceptable?
I'm totally clueless and seem to get conflicting information from different sources.

[stevek64]

I think this very well written document has all the watering details you'll need to know to have healthy plants and trees in our desert:

http://wateruseitwisely.com/wp-conte...ring-Guide.pdf

[M.Unit]

Originally Posted by stevek64

I think this very well written document has all the watering details you'll need to know to have healthy plants and trees in our desert:

http://wateruseitwisely.com/wp-conte...ring-Guide.pdf

Ah yes, thank you for the encouragement...that's the main source I've been using to determine the watering plan. I should say, that's where I came up with the numbers of watering the trees for at least 3 hours once or twice a week and watering the vines/shrubs for an hour once or twice a week. I have yet to implement the plan as I wanted to pick other people's brains who maybe have these sorts of trees/plants if that seems to be a "normal" amount of watering.

Thanks again...I may adjust my system tonight as the trees are scheduled to be watered tomorrow morning and then just keeps tabs on this forum in case other people want to share their success (or lack there of) stories of how they manage their Palo Verdes and other desert adapted plants/shrubs.

[lewdog_5]

I thought with a clay soil that holds more water and doesn't drain well, you would want to water less? Am I confused on that.

[M.Unit]

Originally Posted by lewdog_5

I thought with a clay soil that holds more water and doesn't drain well, you would want to water less? Am I confused on that.

From what I gather, clay soil doesnt absorb the water deeply enough compared to other better draining soils so you have to water longer (with a drip preferably) but less frequently because it retains the water better (obviously, as it's not great at draining).
Is that what you were questioning?
Actually, now that I re-read your comment it appears you're saying the same thing

That main article (WaterWise) was distinguishing between newly planted trees (less than 1-2 yrs planted) vs established trees....it said to be a bit more frequent if they're not established yet and especially if it's in hotter weather. That's why I figured I'd water once a week with those longer watering hours (3.5 hr for the trees and 1 hr for the plants/shrubs) and then once the temps are consistently over 100 I may bump it up to twice a week or once every 10 days depending on how the trees look.

Currently I think my issue is the trees arent getting enough water....because I'm not watering deep enough (i.e for a long enough period of time). They're watered now every 3 days but only for a little over an hour. I think thats why one has lost all it's leaves...interestingly enough, that's the tree that doesnt have any groundcover near it so it doesnt get any "shared" water the way the other tree gets.

I so wish I had a natural green thumb!

[MNSvenska]

I thought that the Palo Verde was a natural desert tree.
So why would it need that much water, even newly planted?

[stevek64]

Originally Posted by M.Unit

Thanks again...I may adjust my system tonight as the trees are scheduled to be watered tomorrow morning and then just keeps tabs on this forum in case other people want to share their success (or lack there of) stories of how they manage their Palo Verdes and other desert adapted plants/shrubs.

I can share what I do. Currently, for our desert museum variety Palo Verdes, I don't have them on an irrigation system. I flood them with a hose once every 3 weeks in summer, about once a month in the spring and fall, and every 45-60 days in the winter. Of course if we get a good rain downpour/soak, I adjust accordingly. When they were young trees, I watered them once a week for 1 year in the summer, about once a month in the winter. These trees started off looking like the Charlie Brown xmas tree, about 2 ft tall, that were planted in May '12 and are now about 20'/20' and very lush and healthy. Our soil here in the Goodyear Foothills is rocky/a bit sandy and drains fast. For newer tree/shrubs, watering them more frequently is usually the norm but even in our sandy soil, I wouldn't water more than once a week for a desert native tree, especially in your heavier/clay like soil. I have an Ironwood tree which is a native Sonoran tree and can survive in our desert on rainfall but during its 1st year after planting it in my backyard, I watered it once a week in the summer to edge some more growth out of it and it didn't mind it at all...no yellowing/funky looking leaves. Your palo verdes will grow faster with more water but there's a fine line of pushing them too hard, creating a too shallow root system, and frankly just wasting water. I'd err on the side of less watering as they are native and can survive in the open desert with very low levels of water though of course they look much better being watered, up to a point. Actually that's why they have green bark....if there's a prolonged dry spell in nature, they will drop all their leaves to save evaporation/water loss yet the can still to the photosynthesis thing via the green bark. Clever desert trees!

[M.Unit]

Originally Posted by MNSvenska

I thought that the Palo Verde was a natural desert tree.
So why would it need that much water, even newly planted?

So when it's newly planted, it needs to get it's roots down deep to become well anchored...the theory is if you do "infrequent" deep watering that it will force the roots to grow deeper. Too frequent watering (especially if it's too short of a period) causes the roots to stay more shallow and when wind storms come, the trees get uprooted.

What is hard for me is that they say while the tree is getting established (from initially planting thru the first year or two) that you should water more frequently but nobody can really seem to agree on what the frequency should be. Some people say once or twice a week, other say once every two, some say once a month.

What almost everyone agrees with is once it's established, you dont really need to water it at all...it can make do with the normal rainfall and if we're not getting enough rains then you can do a deep soak with your hose once during the summer. That I can handle. I just hope my trees make it there healthy enough.

[M.Unit]

Originally Posted by stevek64

I'd err on the side of less watering as they are native and can survive in the open desert with very low levels of water though of course they look much better being watered, up to a point. Actually that's why they have green bark....if there's a prolonged dry spell in nature, they will drop all their leaves to save evaporation/water loss yet the can still to the photosynthesis thing via the green bark. Clever desert trees!

Steve, this is exactly what I'm talking about....you mention they lose their leaves in response to dryness so that's why I'm figuring that since they both dropped their flowers and leaves (one totally lost ALL its leaves) that they're not getting enough water. I currently water a little over an hour twice a week. I think I can safely pull back to once a week as long as I increase the watering time to make sure the water gets down deep. The worksheet on the water wise document suggests somewhere between 3 and 4 hours of deep watering at least once a week. Gonna try that and see how it goes.

[M.Unit]

Stevek64, the schedule you outlined (roughly once every 3 weeks in summer, once a month in spring/fall, and once every 45-60 days in winter) is roughly what Water Wise suggests for established trees. They have a worksheet you can do that will give you an idea of how long to water depending on what kind of emitters you have...
I think I'll definitely stick to that same schedule except increase the frequency a little bit till next year spring time (that would be when the tree is 1.5 yrs old and I would hope it's 'established' by then).
Once they're really established it even talked about not needing any supplemental watering except for maybe a deep soak in the summer to keep your tree blooming instead of it looking too sparse (if you mind the look or course).