2 Soil Moisture Questions

My irrigation is set up on a Flex Daily Schedule. The Allowed Depletion is set at 50%.

Question #1: In one of the zones, the soil moisture is currently 29%. Why is the next watering scheduled for Nov. 24? I assumed that when the Allowed Depletion is reached, watering will begin.

Question #2: I have 5 zones located in one area. The configuration of all 5 zones are identical (e.g. root depth, crop coefficient, soil type, etc.). Why is the soil moisture in one of the zones indicated as 90% & 56-58% for the other 4 zones?

Thank you for your help!

Can you share screenshots of your flex schedule and the zones in question?

Below is a screenshot in reference to my question #2 above. Please note that the “no upcoming runs” is due to the fact that I have switched the controller to the Standby Mode until around March.

Allowed Depletion percent and Soil Moisture percent are two different things, and it can get a bit confusing. The Allowed Depletion you’ve set to 50% does not change, and indicates that half the total moisture in your zone can evaporate (or be used) before you need to water. When none of the water has been used, you’re at 100% in the zone. When 50% of the water has been used (your Allowed Depletion), it’s time to water, and Rachio indicates a Soil Moisture of 0% (none of the Allowed Depletion is left). Like I said, it can be confusing. I think I’d prefer they say it goes from 100% down to 50% and as that’s the minimum, that’s when it will start watering. But that’s the way it is.

I’m assuming you’ve been using the system for some time (a week or so at least)? Even if root depth, crop coefficient, etc. are the same, water runoff due to slope and evaporation due to sun can vary with zone. So while the FIRST time you water, all zones will probably water, after a while, they get out of sync. Which I think is a good thing, so the maximum possible watering time is not used every day. In any event, if a zone doesn’t water when another zone does, they won’t then have the same soil moisture. The longer it runs, the more they’ll be different. What synchronizes them is a lot of rain, filling all zones up. Then you’ll see the zone moisture be closer again.

Hope this helps.

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Thank you for taking the time to answer my questions. That helps a lot.

This is an example of how the interface needs improvement. The MAD is designed the opposite way people think. It should be the actual amount of water in the soil, not the amount of moisture that is in the soil before it decreases to the maximum allowed depletion.

If this were changed, Rachio would not need the Soil Moisture Information, that is in itself confusing.

It means you have 29% of the 50% water you are allowing to be used up. Clear as mud. It should really say 65% and it will water when it reaches 50% or less but that would make to much sense.


I completely agree with this. I had the same confusion when I was beginning with my Rachio system as well. I was always wondering why my moisture levels were going so far below my set limit before it would water again. It didn’t click until I read a similar post here.

FWIW, I only use Rachio’s fixed day scheduling and steer clear from FLEX daily or monthly, & only stick to the weather intelligence settings. Flex daily & monthly settings make my yards too dry in my experience. I’m in the DFW area.

You might try using only fixed days & use the weather intelligence settings.

I agree with that. The flex schedules require way to much messing with to keep things from dieing compared to other, cheaper smart controllers I’ve used.

After using the Flex Daily schedule & tweaking it for a few months, I found that I needed to supplement it periodically with a Fixed schedule in order for my shrubs & other plants to get an adequate amount of water. I haven’t abandoned the Flex Daily schedule, but must admit that the simplicity & predictability of only the Fixed schedule might be worth a try. I’ll wait until next spring.

Only addressing the differing levels of moisture: I ran into a similar situation and after planning around with it, I came to this conclusion.

First, when you say everything is equal for the settings (i.e. crop eff, depletion, depth…) is the sq/ft the same for the zones? The next thing, did you “empty” the list to trigger a watering?

When I was adjusting my settings, I “emptied” the chart/setting. That triggered and the zones to start watering the next day. It started as expected, then after a couple of cycles, it started to vary again. After much troubleshooting/tweaking, I have come to this conclusion. It factors the square footage of a given zone and that will effect watering times. That is the only differing thing now.

With that, I have found an acceptable middle with water settings.

Hope this helps.

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Thank you for your thoughts regarding “square footage”. I’m having a bit of trouble wrapping my head around how square footage will affect watering times. I will certainly check the square footage of my zones.

As I mentioned earlier, I am leaning toward going to a fixed schedule instead. Of my 12 zones, 6 are drip & bubblers. Another zone is for a very small grass area. And finally, the remaining 5 zones are on a native grass hillside which requires little water. So I suspect that the cost savings of a flex schedule for me will be minimal. With a fixed schedule, I can easily make adjustments with predictable results.

Square feet has nothing to do with watering times. It is only used when calculating savings, and that doesn’t occur with Flex Daily. Watering time is simply the water in inches to be applied at one time (Available Water x Root Depth x Allowed Depletion) divided by Nozzle Inches per Hour (times an efficiency factor).

I’m confused. If all of his zones are EXACTLY the same (including slope & evaporation) why wouldn’t they all get the same amount of water? The system won’t know any different since there’s no moisture feedback. Yes, one zone might actually be dryer or wetter based on actual conditions but I don’t see how the system would know that and get the zones out of sync.

Am I missing something?


Yes, that is correct, if all zones have the same soil, vegetation, slope, sunlight, etc., then the water requirements per square foot or acre will be exactly the same. But in my experience, the amount of water on each zone, entered in Nozzle Inches per Hour, are almost never identical. Differences in size and shape of zone, placing and type of sprinkler heads, often vary. Even if they don’t, the total piping length to each zone, which definitely WILL be different, varies.

Nozzle Inches per Hour is IMHO the most important and critical thing in properly setting up an irrigation timer, and also the most difficult to determine. Using default values is a start, but measuring flow GPM and calculating Area, and using the formula:

Nozzle Inches per Hour = Water Flow (GPM) / Area (sq ft) x 96.25

will give you a much better value than the default. I think if you calculate this for each zone, you will find it to vary for each zone.

Rachio should follow the same MAD scenario as the as The Irrigation Association, IA.org, uses for the Certified Landscape Irrigation Auditor course. That way it would not be confusing to people who are trained to manage water scientifically.

That link doesn’t work. Do you have another?

Sorry. https://www.irrigation.org/

Sorry for the mistake. It is https://www.irrigation.org/.