Setting Up Flex Daily in PHX with Mixed Plant Type

You predicted my summer watering frequency.

My flex daily runs approximately every 5 days on the combined shrub and tree drip. It wasn’t too hard of an adjustment for my plants even for the hottest June ever. I’m surprised they adapted to the flex schedule since I had got the Rachio 3 in December 2020.

My plants are happier than ever with the lowest June water bill yet!

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What are your settings for your tree/shrub drip zone?


I have the default shrub root depth and the default tree crop coefficient

I might back down the crop coefficient or increase the root depth next year, but I’m letting the plants adjust in the meantime. I’ve only had my Rachio 3 since December.

I can’t make the shrubs completely happy and the trees at the same time on the same zone

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You have spray type as emitter and slope as steep.
My understanding is that slope only affects the smart soak cycle. So with a steep slope, there will be longer soak times.

However, I thought I read that if you select emitter, the system will not do a smart soak. For a smart soak, something other than emitter must be selected. Is that correct or not?

I have drip emitters that are 1gph 2gph and 4gph for the shrubs and trees. I selected steep as a few areas are steep even though it doesn’t cycle and soak. I probably don’t even need it anyways with the low flow.

If you have the spray head set as any type of “Drip”, cycle and soak is not used.

Yes, I did see that. I don’t need cycle and soak for the tree/shrub zones. I have it that way for the exact inputs

Why is the soil moisture capped at 110%? Is there a reason why it isn’t capped at a higher or lower value?

While I agree that it could be slightly higher (it used to be 120% LONG ago), I believe the thought behind that is that there is only so much water that will stay in the root zone regardless of whether it is 1" of water, or 6" of water. The same 1" will percolate through the soil at the same rate as 6".

I can kind of follow this idea when I flood irrigate my property. My front lawn areas will fill with 6-8" of water with 1 hour of flood irrigation run time. That water will percolate through the soil within 24 hours. Within a few days, the ground is “dry” again.

What are your opinions of this chart?

Specifically the recommendations for the following vs Rachio defaults

the root depth,
crop coefficients
nozzle inch/hour

Well the nozzle inches per hour should really be calculated.

Run a zone for 5 mins and take the before and after water meter reading.

(Area / Mins / Quantity) * 60

My calculations from azdavidr and water use it wisely calculator is approximately 0.4"/hr. I selected number of emitters and and a gph for each plant to match a 0.4"/hr precipitation rate, except for establishing plants, which I water extra.

Do you have a link you can share for this @ECOBEARD ? It looks like an interesting reference to have handy.

EDIT: Found it!

https://www.gilbertaz.gov/home/showpublisheddocument/33896/637383685631870000

@azdavidr @tmcgahey

What are your settings for your tree zones and shrub zones?

The table crop coefficient range and root depth are lower for trees than the Rachio defaults.

What are your settings for your tree zones and shrub zones?

I wonder if I should lower my mixed tree and shrub zones crop coefficient to 70% from 75%.The plants had a full year to adjust to the Rachio 3 settings I had before. I recently rose the root depth to 16” from 15.8”. Should I change the efficiency from the default drip?

I would like to get more water savings without sacrificing the plant health. I cut the total water bill in 2021 by 1/3 compared to 2020 with the Rachio 3 with no known adverse affects on the plants. In fact, they appear healthier now than before Rachio.



It would confuse things if I showed you mine right now. I have a bunch of new shrubs that are messing up what I would normally have. I will point out that my Available Water is 0.12 in/in and my Nozzle Inches Per Hour is 0.16in. Where did you get the numbers that you’re using?

The crop coefficient will depend on the tree type. Plants that need to be watered more will require a higher crop coefficient. For example, a Ficus would likely need a higher CC than a Mesquite.

Maybe, but keep your eye on the schedule and trees after the change. In my case what worked for me in the fall, winter & spring did not work in the summer. I ended up setting my crop coefficient based on the summer needs. I have Ficus trees and I think I was at ~80%.

That’s a pretty small change. I wouldn’t worry about that making too much of a difference.

This is where I got my Available Water number. It’s an important setting to get right before all of the other changes you’ll make. Setting this right overrides the Soil Type you have, and should be more accurate. I don’t think we have a lot of pure Loam in AZ.

Have you played around with this spreadsheet ? That’s how I set my numbers for drip.

@azdavidr @tmcgahey

I got my precipitation rate from a combination of your spreadsheet and this link below. They both came out to around the same 0.4”/h precipitation number.

http://irrigation.wsu.edu/Content/Calculators/Drip/Drip-Line-Rate.php

I have Gilman loam based on the soil survey link. It says it’s 2”/1’ which is the same as the default 0.17 Rachio loam.

Are the Rachio 3 default root depths for a given plant type

1 maximum root depth?
2 starting root depth?
3 average root depth?
4 established root depth?

I had no issues last year at 0.75 crop coefficient and a 15.8” root depth, even in the 1st year on Rachio, which included the very hot June 2021. I’m assuming I should not go any higher than 18” with the shrubs mixed into the zone.

My plants are mixed from eucalyptus, ash, elm, oak, citrus, mesquites, lantana, bougainvillea, palm trees and other various fruit trees. That’s why I errored on the higher end of the crop coefficient between the shrubs and trees, and the default root depth of the shrubs.

My Rachio settings I posted above worked so well all of last year that I’m hoping to find a way to tweak the settings for even more water savings without stunting the plants this year vs 2021.

The instructions for the Web Soil Survey should lead you to a page that shows you the actual available water number, not just a soil type. Did you see that?

Regardless, if you had good success last year, especially through the summer, I would make any changes from here on out gradual. Our summer will test out the settings the most, so make sure you keep an eye on things when it starts to heat up.

@azdavidr


I increased the root depth to 18” for the mixed shrubs and tree zones a few days ago. The plants have been using 15.75-16” watering setting for over a year. I’m assuming they can handle the 2 inch increase in root depth.