It rained .2 inches

And the Iro says it won’t water until September 13th in some zones and September 3rd in others!!! Interestingly they are all the same crop/grass.

Just for reference the ET yesterday was around .2 with 92 as a high and dewpoint in the low 30’s

If you want to reach out to [] they can review your schedule make sure things are set appropriately.

Looking at the zone moisture level graphs will also give a good explanation of why things will or will not be running.


@franz everything has been working correctly and I don’t see anything broken. However, the Iro seems to be really banking on .3 inches of rain 7 days out. Not sure how much faith you can put into precip forecasts more than 3 days out. Combine that with lower ET values predicted and the moisture graphs make sense.

And that is even cut by 50% (the forecast must be .6 inches of rain).

We love feedback and real-user input. If you have any suggestions for optimization please let us know…maybe as the forecast days go out, we drop the forecast even more? Right now the current rule is:

60% chance of rain or greater, we take forecast at 100% face value.
Less than 60% chance of rain we take the forecast at 50% face value.



This is VERY unscientific, but if our local weather forecasters give us a 10-20% chance of rain in the next day, we can pretty much know that we are NOT going to get rain!

Is there any way at all that you could do something different for beds that are described as Annuals?? I know that is just root depth into the equation, but I would rather have the system err on the side of a little too much water for my annuals than too little. With my lawn, shrubs, and even my perennials, I really don’t get upset when it is going to possibly underwater. But if the system under waters my annuals, I can lose them.

I know I could go to fixed schedules for annuals, but I’m hard headed and I want to see the flex scheduling work. And in my case, my County gives me a lower water rate if I am using all smart water schedules.

The problem is that we get an aggregate (PoP) which is very unscientific.

We don’t receive C (confidence) or A (area)…so we have no idea how PoP was derived.

If there is a better way to do this, I will definitely implement.

For a while we took the PoP x forecasted precipitation, but that didn’t seem right either, and we were underestimating rain amounts…

Open for suggestions :wink:


I am not sure looking at precipitation probabilities or amounts past 3 days makes any sense at all. I would just look at temps and such for ET and calculate a schedule based off that. You will always be off one way or another looking out that far. Is there any reason for doing so in the product for other reasons?

My scheduled zones for the 13th are now on the 10th.

Here are images from my station on wunderground and the iro moisture level. It is hard to reconcile the too.

Flex auto-corrects every day with observations, so even if there is some weather event in the far off future with a large amount of predicted precipitation, that doesn’t affect whether or not we run in the next day or so…

In a future release I want to add the ability to artificially increase/decrease (offset) crop evapotranspiration which ultimately has a large part in dictating the watering frequency. Then no one will have to learn about MAD, root zone depth, etc.

We will have a dial that allows you to increase/decrease watering frequency.


Maybe we are talking about 2 different things. I don’t necessarily care about making watering more frequent. Although I agree that is a nice feature to add for simplicity. I trust the system (for the most part) to get things right since I believe the data inputs are reasonably close to accurate (now). My lawn didn’t die last month. Maybe a little browner than normal but it was warm, didn’t rain much, and most of the neighbors yards were looking the same. But I know where you are coming from. Not everybody cares to understand things so keep it simple.

What is somewhat bothersome is the watering schedule. It is always just wrong all the time. I think it is related to using UTC for date/times. For example watering starting at 10pm MDT on the 29th always shows as the watering starting at 10pm on the 30th in the schedule. So that future dated schedule above where I said the 10th, actually means it will water the evening of the 9th. It took me a while to figure this out.

So imagine this scenario. You notice the grass is starting to wilt a bit and check the schedule on the device. Nothing is scheduled for today, but shows watering tomorrow beginning at 10pm. So you go and empty the zone to make it water tonight and notice it is already at 98% because it is going to actually water tonight. For the first few weeks I had this device, there was no empty/fill and I believe moisture balance in the mobile app. So things were even more problematic to fix even though they didn’t need fixing.

I hope this makes sense. To me there are really two issues. The first being UTC dates/times. The second is a display issue in the mobile app right below the schedule where is says the next scheduled watering time is X at Y. This also pulls the UTC date for X.

Hi there. I wonder if part of the problem might be that you are watering in the evening instead of in the morning. My understanding is that the Iro updates and does whatever math it does with these flex zones in the wee hours of the early morning. So if your schedule is set to water at night then you might end up being perpetually a day behind. I could be 100% wrong about this; I’m sure that @franz will give a better response. :slight_smile:

Plus, I’m no expert, but my understanding is that in general it’s better to water in the morning around sunrise. Watering at 10 PM means that the plants will stay wet all night and this promotes mold and fungus growth.


With the frequency of this topic of how forecasted weather works, is discussed, further leads to the argument that this function should only be an option such as Smart Cycling. Utilizing forecasted weather is quit difficult, watering based off of forecasted weather can be a risk proposition in certain parts of the country where rainfall can be quite different from 1 location to another within a very small area. Once a watering event is missed or stopped you can’t get it back. I’d rather make the savings up on the back end using only real time collected data to make decisions on scheduling. If i’m not mistaken this is the method used during S.W.A.T. accreditation.

I realize that using forecasted weather may work in some parts of the country but in my neck of the woods a 60% chance of precipitation only means about a 5% chance of that precipitation falling at my location. Unless you are using 2 Square Kilometer weather modeling i’ll let my rain sensor interrupt a scheduled event if the precipitation actually occurs.

I can think of dozens of other questions for you to answer on how weather forecasting works, but in the end, I believe getting back to the basics of why the system works is most important.

Turf and Landscape Irrigation System Smart Controllers –
Climatologically Based
1.0 Scope
"This evaluation will be accomplished by creating a virtual landscape subjected to a
representative climate and to evaluate the ability of individual controllers to adequately and
efficiently irrigate that landscape. The individual zones within the landscape will represent a
range of exposure, soil types and agronomic conditions. As a standard from which to judge the
controller’s performance, a detailed moisture balance calculation will be made for each zone.
The total accumulated deficit over time will be a measure of the adequacy. The accumulated
surplus of applied water over time will be a measure of system efficiency. Water applied
beyond the soil’s ability to absorb it will be characterized as runoff, further degrading the
application efficiency. The study will use ASCE-EWRI data from a representative accredited
weather station. Further the study is not meant to include individualized water management
strategies aimed at producing special physiological affects. If the controller maintains root zone
moistures at the levels specified, the protocol assumes that the crop growth and quality will be
adequate. The moisture balance calculation will assume that the plant materials are functioning
as mature plants. "Source 8th Draft Testing Protocol Rev. 3 – September 2008 © 2008 Irrigation Association

I do not see anything here about watering based off of Weather forcast, only real time data.

If this is to be implemented, maybe you should test if it would still pass the SWAT testing. You are lumping allot of variables into one function, each that has a specific function within the equations that produce the outcomes of the watering schedules. I know you are trying to create simplicity, just make sure you are simplifying the right components. If It passes great!

Yeah, things are a bit different here due to the desert like climate and evaporation being the greater concern.

10pm-6am is suggested for watering grass. Ideally I would like to get my schedule set for just after midnight (due to winds), but there is a possibility that if all the zones will run the schedule will take me past sunrise, especially in middle of summer.

We are working on having the soil moisture graph render in the device’s timezone :wink:

Hopefully the changes we are working on will remedy this. Right @tburch :smile: ?


It’s actually one hour before the schedule start, whenever that may be.

Agreed. Always water coolest part of the day. I start mine at 3:30AM.


So these are good points. But…we mostly use the forecast for today for ET (we can’t use an observation since you need max/min temps for the day). I agree the forecasted precip is problematic…always looking for a better solution. I’d hate to completely ignore today’s forecasted precip…



@franz speaking of ET, do you look back in time once a day is over to correct forecasted ET vs actual ET? This number really seems to be the most crtical value for accurate moisture levels. I have noticed a decent deviation between what the Iro says the ET value is versus what our town records for ET.

Looking at 8/31 for example the town is saying ET was .26 and the iro shows 0.07!!! Even if you throw out that day as bad data, it is very common to see ET values at or above .2 which I have never seen from the Iro. What kind of daily ET numbers are normal at KDEN? How about where folks in the office live?

Is someone’s math incorrect?

The answer is ‘yes’ (look back in time).

But there is an acknowledged bug that causes another day lag time to recover. Total lag time at the moment is 3 days from the time it was supposed to (not) water (due to forcasted rain) to watering to recover from the fact that it didn’t actually rain.

The time zone problem and this problem are two of the most serious problems I see flex scheduling have.

Best regards,


Yes, everything is auto-corrected, we always defer to observations when in the past.

We calculate ET based on chosen weather station, or closest to the Iro. I can’t explain why those values are so different, would need to know the exact values your town is using to derive ET.