ET based (weather station), fixed day, watering available?

Is there a scheduling option to run on my Gen 2 (2.6) for:

  1. Fixed Days
  2. Using ET data from our local weather station to determine run duration (minutes).

I want to water deeply for a duration that replaces ET since the last irrigation but I don’t want the sprinklers to run whenever they want. I don’t want sprinklers running before I mow or just before an outdoor lawn party. I also don’t want them running for a short duration as I want to encourage deep root growth with deep watering (longer run times).

I live in the Central Valley in CA where summer temperatures (ET) can vary considerably day to day with essentially no rain between April and November. For this reason I don’t want to use historical weather data for my run times.

A specific example of something I’m familiar with is the Weathermatic SL 1600 timer with a SLW5 weather monitor. This unit sends nightly ET info to the timer and if no watering is scheduled for that day the ET data (“run time”) is put into memory and accumulates until the next scheduled run day. Then on the next scheduled run day ET since the last watering is basically applied to replace what transpired and evaporated over that period. of time.

To complicate things a bit I have two Gen2 units on my property with 25 zones, with multiple sprinkler/drip types, which makes available hours in the day to run a challenge.

I think duration changes happen when there is seasonal adjustment on fixed or monthly flex schedules. But it may not be as drastic as you want.

Have you tried setting up a flex schedule with specific watering days? Iro by default wants to do deep watering and should if your zones are set up properly. And with flex daily you can control which days it runs. For mowing and parties (since they don’t always happen on the same day of week for me) I use the rain delay option and let the zone refill on the next allowed watering day. Hope that’s somewhat helpful.

Thanks for the interest/comment.
I haven’t set up a flex schedule as yet. When I started to I think was when I started to question how doing so would both water on set days and utilize the input of our local weather station. It seemed as though I would get monthly adjustments based on historical data only.

Just to clarify; what you describe is flex monthly which uses historical trends and creates a schedule at the beginning of each month. At each allowed watering day Flex daily will decide if the zone needs to run based on the ET that’s occurred since the last watering. I’ll defer to people who’ve had Iro longer to correct me if I’ve misspoken :smile:

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A Rachio phone rep, as I understood him, said that with Flex daily the Rachio will decide if it needs to run and if so it will do so for a set amount of run time. Then, if more is needed than the set amount of run time it runs again for the same amount of set time. Didn’t really make sense to me, maybe I misunderstood him.

I want to run on specific days, starting at a specific time, and have the run times determined by my local weather station (ET) and the parameters I have set for each zone (sprinkler type, plant type, soil etc.)

Does anyone know if this can be done?

You can run flex daily on any day of the week you want at a specific starting time. You can edit your current flex daily in the ‘Edit Schedule’ function. The run times for flex daily are determined by weather and all the settings you plug in for your zone.

That is what I was hoping I could do but thought I got thrown a curve by the Rachio tech by telling me the run times were fixed. I’ll give it a try.


Does anyone know if I need to delete schedule in order to change it from Fixed Days to Flex?
When I go through “Edit Water Schedule” and then to schedule type I can’t change the fixed days to flex.

@GmanDan You don’t need to delete the old one. I’d suggest you just go into it and disable it. Then you create the new Flex schedule. There’s not a way to go into an existing schedule and change schedule ‘types’ that I know of.

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I believe the run time ARE fixed. For a given zone, the soil type and plants will require a given run time, say 20 minutes.

When it is time for the zone to water, it will run for 20 minutes. AFAIK, there id not 10 minute topoff function. If the zone doesn’t need 20 minues of water, then the scheduled will be delayed.

This is based on my “water any day” experience, and maybe for set days it will top off a zone, but I have not experienced it myself.

Agree that it is a fixed amount of watering time for flex daily. I do believe the only exception to that is if rain is forecast, it would decrease the watering time by the amount of rain that is expected.

In general, I believe this to be the best approach…

However, it fails until the condition of a highly constrained watering schedule. In this case, the best thing to do (IMHO) would be to top off the zone enough to make it to the next watering day based on current forecasts.

My understanding is that the amount of water plants need is the replacement of what has evaporated from the soil and been used (transpired) by the plants. This is called “ET” and is calculated by plant type and the weather since the last application of water.
Setting sprinkler, soil, plant type is essential but so is weather data. It remains unclear to me how Rachio uses weather data when calculating run times. I don’t understand how one can use a set number of minutes of run time when assessing plant water needs.

@GmanDan I think the idea is that you want to get the water down to the defined root depth. Combined with that the soil can only hold so much usable water. The duration is then set to maintain at least the maximum allowed depletion.

For my garden below, run_time = root_depth * AW * MAD = 4 * 0.17 * 0.5 = 0.34 in

I think this is how it works anyway. So you would be right, the weather is not used for the default run time. Since I live in a desert I don’t have a lot of experience with rainfall, so I’m unsure if the irrigation time would be adjusted in certain rain scenarios. :wink: I didn’t think that was the case but I could be wrong.

My run times definitely did not change based off weather conditions. My grass ran the same time when it was in the 90’s and when it was 115. The moisture level just dropped that much faster, causing it to water sooner.

It sounds like what the Rachio tech told me on the phone is what you have experienced regarding the run times, run times are set and occur more frequently if needed.
But I want fixed days only! And, how can such a set-up save water if it can only run a set amount each time which might apply too much or too little.
I don’t know about you but I’m still not confident in how to set up the Rachio to run as closely to what I want as possible.