Compensating for heat

You have some good points. Our city restrictions don’t allow run off and that’s what I get if I water for longer periods of time. If I could water a few times a day to compensate that probably would do it, just let me know how to set that up. The reason I purchased this unit was to vary the watering with temperature and seasonal shifts. If I wanted a fixed dumb watering solution I would have stayed with my conventional controller. I’m confident with a few tweaks your system can perform very well. Thanks again!


My recommendations are:

  • Use our smart/cycle feature if you are concerned with runoff. I’d set it up manually in the schedule max 7 minutes with 30 minute soak for the zones you are concerned about. Here is more information.
  • Flex daily will ultimately do this but needs some fine tuning in the beginning to setup. I’d actually just start with one grass zone and see how it performs before rolling out to other zones. It could take a week or two to get used to how it waters. The moisture graph will show simulated watering for the next two weeks so there are no surprises. I’d start with the defaults that we generate for the zone and then we can go from there. Hope this helps.

The best weathering for turf is less freaquently but for a longer duration, I’m not sure if Rachio offers a cycle soak feature I will have to look. This feature will allow for longer watering with a delay in watering to allow to leach into soil then will resume watering so you do not get the water run off and waste of water. When you water more often the water doesn’t get a chance to leach down into the soil and the roots to follow increasing root depth. When watering more often the roots stay shallow and will dry out in extreme temps. Good luck

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Yes, I agree with watering less often but when your in a desert with temperatures @115 F crushed granite as a base soil you don’t have many options. I’ve tried it and grass turns brown very quickly. Long term the goal is to stretch out watering intervals but for now I can’t. Even if I could switch between fixed and smart watering scemes based on temperature would help.
Apparently you can’t adjust to a full watering cycle using smart watering because of current design rationale.

A quick observation - Your efficiency is listed as 80% - that simply is not possible with sprinklers.

Thank you for your support! That’s what I’m looking for! I need to understand all of the parameters so I can make sense out of it!!!

I and others here live in a desert with those temps and crappy desert soil and we’re on Flex Daily. I don’t water daily in those temps. The system can handle it but your lawn/roots seems trained to to expect water daily or even multiple times a day. That isn’t a controller issue.

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I agree but the summer isn’t the time to make changes from the way the old controller was set up. It will take time to Transition and test.


This is simply false. What works for you doesn’t necessarily work for someone else. I got .07 AWC coarse sand. If I don’t water daily the lawn will struggle in the heat. The problem sounds like he has the wrong soil in his settings. If he is getting runoff with such short durations I highly doubt he has sand (.07)

It’s not false. It works for me in a 115F desert climate, which is what I stated. He also said that he had hard soil, not sand. Had he said he had sand I would have answered accordingly. Even his moisture chart isn’t showing that. If he had sand it would have been bottoming out and that’s clearly not what his moisture chart is showing.

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Yes because you have different soil. Like I said what works for you doesnt work for everyone. As Franz mentioned earlier he has .07 AWC indicating sand. So what rachio thinks the soil moisture is doesn’t reflect what the soil conditions are (bad information = bad results). If he is getting runoff with only a few minutes watering then he must have a different soil which in turn means a different AWC.

My bad, I didn’t see that part. I agree, the soil setting is probably a big factor.

The reason it’s set to sand is to try to get the controller to water more often with heat.

So now because this controller doesn’t seem to be able to fully compensate for heat, I’m looking at going back to the same for fixed schedule as the hunter controller I had previously. I can’t simulate weather changed and predict that this thing is going do.
With a fixed schedule how do I set different zones to water on different days within the same fixed schedule? It seems like day skipping be is applied to all zones only? I need zones that skip days and some that water multiple times. Thanks.

I know that intuitively you would think this change would help, but things get pretty screwy when your soil settings are off. I’d recommend trying to go back to what you truly think the soil is. If you haven’t already, use the Web Soil Survey guide. Then follow up and make sure that the rest of your settings are pretty close, especially root depth and precipitation rate. Once you have all that set look at your moisture graph again and see what it’s predicting. Tweaks are easier once all that stuff is close to reality.

As an example, here is my chart from this week, when temps were hovering around 100F. You can see that it irrigated every third day.


This coming week temps are climbing to the 111-115F range. It is predicting every other day. In some cases it will actually go for two days in a row, then take a day off.


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Experts advise that we irrigate 3 days in advance if we know a heat spell is on the way. In addition, there should be a setting for Cool Season irrigation for CA native plants and a Santa Ana Wind setting for giving plants extra water since their transpiration (cooling system) is destroyed by the hot winds. Santa Ana’s take water from the soil AND from the leaves.

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Here…here I concur but first I need to spend so much time edumicatimg myself on the details of using this smart controller. I’ve ordered a rain gauge and need time to study. Thank you!


Ok, I measured the front lawn. In what appears to be the poorest location I measured 0.015" per minute. On 100 degree days I need to water for 10 minutes in the early am and 7 minutes around 1 pm to keep the grass green every day. Now what do I need to do to figure out all the settings and make this system work?

If you feel that you in fact NEED to water in this way, your only option is setting up 2 fixed schedules, one to starts in the morning, and the other in the afternoon.


I say get all the flex settings as accurate as possible. Sounds like your catch can was 1"per hour. If things are still stressed, increase the crop coefficient in 5% increments until it seems right.

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