Only 5 waterings in August!


We’ve had some scattered storms through August and another one tonight that have continued to push my flex daily schedule out.

The storm tonight moves my scheduling out to the beginning of September, which means in August (second hottest month in Colorado) I watered 1.25 times per week, not too bad.

So cool how you can watch my PWS record precipitation, then a few minutes later see the flex schedule graph accurately record the .30 inches of rain, and then magically move!

To follow the entire flex watering saga.

:cheers: :colorado:


I’ve been known to immediately go to my PWS site to watch the precip numbers… sadly even at 3am. I didn’t receive an insane amount of rain this August with our monsoons, but the Rachio still allowed me to use about half the amount of water in Aug vs July based off the “Monthly Water Use” info on the app.


Yes, I’m that guy now.

…but not that bad :wink:



I only had 10 waterings for Aug. ( ) For Dallas area that’s pretty good.

For this month Aug. I put down half the amount of water I put down last year Aug. (15 vs 37 hrs.) ( ). Part reason for this favorable performance is better programming of the Rachio this year (buffalo grass = trees, St. Augustein = warm season grass, zoysia grass = shrubs, flowers = annual, everything else as it actually is (soil, sprinkler heads, sunshine, slope, etc.))

The other part reason is that this year Aug. has been cooler and with more rain: 610 CDDs this Aug. versus 690 CDDs last Aug. ( ).

Best regards,



admit to the same crime…checking my phone on what’s watering when i wake up after 2a… or, even better, if I hear rain.
as the master of PWS rachiohq you are most certainly getting a hall pass from us :innocent:


Awesome! I just switched from fixed to flex and hope to see similar results!



I can help you review your schedule if you need it!



Curious how September turned out for you @franz since there wasn’t any rain. The Iro works well at saving water when there is precipitation and a good pws.

I crushed my water allocation for September. Highest ever water bill - same usage as July. I found myself dialing my coefficients back to 70 or lower in all my zones. It was almost as if the Iro didn’t take the low nightly temps into account effectively. Maybe something to take a look at. High 60 Low 39 with ET .12???

I will probably go back to every 3rd day schedules next year. Just seems to work better…



I tallied it up and had 8 waterings for September.

What is the irrigation amount applied to your lawn? That will drive the frequency. For instance mine is .48 inches, so in your scenario with an ET of .12 inches and no precipitation I would be watering every 4 days (4 x .12 = .48).



I’m watching my Rachio performance very carefully as we enter into the winter months here in the Dallas area. Rachio appears to perform well with making automatic adjustments for rainfall.

My questions is, does it do equally well with fluctuating ambient air temp?

So far my Rachio water use for this month is right at 5 hrs - slightly above what it was at this same exact point a month ago (see ). Still running my Rachio fully automatic, and, not allowing any adjustments to the system.

Certainly rainfall or lack there of influences how my Rachio performs. But how responsive is it to ambient air temp?

The 30 day moving average ambient air temp has dropped from a high of 89 degrees F exactly 2 months ago to 75 at the moment:
( - red line).

And soil temperature has dropped from 80 degrees also exactly 2 months ago to 73 at the moment (same chart, black or blue line).

I’m watching with keen interest. I’m expecting my Rachio allowed water usage to go to near zero as we work through the Fall season and get into Winter months.

Best regards,



I see .48 inches applied as well, but the ET isn’t constant. I can’t go back into September to see what was going on. From what I remember though the zones with crop coefficient at 80 or 90 ran every other day to every 3 days. This is what I saw in July too, with much higher nighttime temps.

For example yesterday’s ET was .04 with a high of 48 and a low of 35 and cloud cover basically all day. So 0 wind, high humidity, and low to zero solar radiation.



If you are looking to have less frequent waterings, managed allowed depletion, root zone depth, or crop coefficient are a good place to start.

Here is some more information on the different levers. Once everything is dialed in to the frequency you like, it should be mostly automatic.

Just let us know if you have any followup questions or feedback.



@franz that is the problem. I had things dialed in for summer heat but the system isn’t dialing back the way it needs to when the cooler nights (and days) come along.

Something to ponder. Why the same settings used the same amount of water in July and September? We didn’t get much in precip in July here either and came close to 100.


The enhancement for next year I’d like to make is a way for you to opt in to have the system automatically modify crop coefficient throughout the season (once a month).

It’s hard to tell without seeing all the data. I’m curious so I’ll see if I can do some research and add up your ET for July and September to see if anything is easily identified.




I did some research looking at the raw factors that drive flex daily which are evapotranspiration (ET) and precipitation.

Your data for July (8.043 in) had higher ET than September (5.263 in) which makes sense, but July also had significantly more rain (2.051 in) than September (.39 in).

Cumulative ET (ET - precip) for July was 5.992 in and for September was 4.873 in.

To the best of my knowledge this is why you would have seen roughly the same watering in July and September.

Now, whether or not this was the correct amount of watering for your yard I can’t answer that. It would depend on if the yard is too stressed, or too over watered.

year_month evapotranspiration observed_precipitation 
---------- ------------------ ---------------------- 
2016-10    2.249              0.12                   
2016-09    5.263              0.39                   
2016-08    6.832              0.85                   
2016-07    8.043              2.051                   
2016-06    8.357              2.531                  
2016-05    5.718              2.835                  
2016-04    5.039              2.480                  
2016-03    4.087              2.283                  
2016-02    2.259              0.827                  
2016-01    0.879              0.275 

Hope this helps.

:cheers: :colorado:


I hope the above was written to illustrate that lower monthly ET is a function of colder termperatures. And that the Rachio is algorithmically produced to correctly make this calculation.

What I don’t know is if the Rachio is also algorithmically produced to also adjust ET as a function of when it’s a growing season and when it’s not. I suspect the answer here is ‘no.’

WRT lower ET as a function of colder temps, indeed it’s getting cooler in Dallas this month. Cooling degree days are looking to come in at half of what they were in Sept. ( ).

So you would think waterings would be much less this month. So far it’s 12, compared to 15 last month. That’s not a lot of difference. But what’s happened is those zones associated with buffalo grass (watered as ‘trees’) and zoysia grass (watered as bushes) have reduced frequency a good amount. Thus, hours of watering is indeed lower, from about 15 hrs last month to about 9 hrs at the moment for this month ( ) I can see that the Zoysia grass has one more watering coming in Oct., with no rain in sight, so water usage will end up at month to be lower, but not substantially lower. Indeed we have not had much rain this month.

Best regards,



@franz, like you I love my flex schedule. The one thing I don’t quite understand in this thread is the focus on the number of watering days. I for my part revel the fact that every single zone only gets water when needed, which quite often results in several watering events per week, but in aggregate leading to much lower water quantities per month than with my fixed schedules in the past with non smart controllers.

@Hooper, In NC we also had a very hot summer and during the high temps I was tracking well. I thought my ET values still tracked well when the days got shorter and cooler, but my % of sunshine/shade picture clearly changed with the sun trajectory and I had to adjust this zone parameter to be in line with my observation. Hope this helps.


Yep. This was the issue. Sun angle = more shade and less water needed. I just didn’t back the coefficients down in time to not blow up my water bill.

If you water every 3rd day, all of these problems go away in a climate without precipitation like here.

There is still value in being able to remotely control the system from afar or your couch. It also makes blowouts dead simple.


I was perplexed too when @franz focused attention on number of watering days per month as a measure of performance.

Like you, I believe a key competitive advantage the Rachio has is every (each) zone is independently tracked for automated watering only when needed.

Parenthetically, I can see why expansion beyond 16 zones, mainly for commercial, city parks and large land areas, is a big challenge for Rachio Gen 3. Each details for each zone has to be tracked. And that’s a lot of independent zoning to coordinate as one unit.

Best regards,



I have a relatively simple yard with 3 zones that are all running largely on the same cadence (mostly same zone characteristics). The reason I focused on number of watering days for the month is that I can compare that to a typical set and forget controller for the month of August. It’s just an easy way for my mind to deduce how much water I would have applied without dynamic daily adjusting. For August in Colorado you would probably be on either a 2 or 3 day interval. With a 2 day interval total number of waterings would be 15 and with a 3 day interval total number waterings would be 10. Comparing my actual 5 waterings hopefully shows more efficiency and intelligence in relation to a simple timer. Am I missing something? :wink:

For next year I want to re-incorporate automatic crop coefficient adjustment for different times of the year. No promises, but it’s on my road map.

Wow, I hadn’t even thought of this. :relaxed: