Not enough water when it is hot, too much when it cools off

I live in 5a and I have fescue grass. My soil is mostly clay. Probably silty clay to clay loam. I currently have the schedule set to Flex Daily and I have the weather information set to a personal weather station that is about two miles from my house. In the heat of summer, when the temps are regularly above 90F, my grass dries out to the point that I regularly have to go into the app and reset the soil moisture percent back down to zero so that it forces an extra watering day. Areas of my lawn that are well shaded do not however dry out. They are watered nearly perfectly. But now that it is cooling off a bit and the temps are in the 70s, my lawn is getting overwatered to the point that mushrooms are coming up and I am skipping watering days. I am just wondering what settings I need to change in order to get it to water more when it is hot and less when it is cool. The whole point of using the Rachio and setting it to flex daily is so that you don’t have to mess with the controller and the settings and the watering schedule. It seems however that the “smart” watering schedule only gets it right when the temps are right around 80F.

Can you share you zone settings?

Each of my zones are set at the default settings for cool season grasses and silty clay. I have 7 zones and they each have a different type of sprinkler head and slope and sunlight exposure and I have set those appropriately.

Give this a look.

I have seen that page before. I can easily move the time up or down or I can change some of the advanced settings, But the problem is that if I change one of the settings so that it waters more often in the heat of summer, then I have to adjust it as the temp cools down. What’s the point of a “smart” watering system if I have to constantly change the settings so that it gets the watering correct? If I wanted to constantly adjust the settings, I would put my standard water timer back on.

It seems to me that the rachio algorithm for watering is wrong. It doesn’t water enough when it is hot outside and it waters too much when it is cool. There are no settings that I can change to tell it to water more when it is hot and less when it is cool. That is what rachio is supposed to do out of the box when you tell it to use flex schedules and you hook it to a weather station.

If the problem is fixed by getting a v3 rather than my v2, with it’s improved weather intelligence then I would do that. I am just not sure it would fix the problem.

I have said this before and I will say it again, rachio needs to integrate some sort of button or feature within the app that asks if the zone is getting too much or too little water and it auto adjusts.


Take a look at this thread. Once you get your settings right, you shouldn’t have to mess with them.

Two settings you really need to look at are root depth and nozzle inches per hour. Most likely, getting those set right will get you fixed.

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I have had my rachio v2 for about 4 years now. I have adjusted and readjusted the settings. I have been through all of these guides. I have been through the setup of each zone. I have entered in my soil types and my nozzle types and their flow rates. I have literally dug up large chunks of grass in each zone to measure the depth of their roots. I have put out catch cups to measure the amount of water that is spread per minute in each zone. I have added sprinklers in certain zones for better coverage and removed other sprinklers that had too much coverage. I had changed nozzle types on many sprinklers in order to get more uniform spread and ensure I hit every corner of my yard without getting dry spots in the middle. I have spent numerous hours and a decent chunk of money trying to get the watering of my lawn to work correctly.

After all of that, my problem still remains. When it has been in the 90s frequently, my grass dries out and turns brown. I can stick a shovel in the ground and dig up a chunk of grass and the soil will be bone dry. Except my app will claim that moisture content should be 60% and it doesn’t plan on watering until the morning after tomorrow. So I tell my app that the moisture content is 0% in order for it to force a soak. And then I repeat the process a few days later.

When it is cooler, I have the opposite problem. I will mow my yard and the ground is sopping wet. There are mushrooms growing. The rachio plans on watering the follow day because it says that the moisture content is currently 30% despite it being sopping wet as I walk through it. And if I put a shovel into it, it is wet for a solid 12 inches down.

So no matter how I change the settings, none of them is going to tell my rachio to water more when it is hot and less when it is cold. I can’t imagine that my problem is unique. I live in the Midwest with clay soil and the potential for hot summers with somewhat high humidity and very cool spring and fall with a normally decent amount of rain.

Why can’t it be as simple as telling the rachio that the ground is already wet, or still wet from the last watering and so it will skip a watering or back off a bit? Or tell the rachio that the grass/ground is dry and so it has been underwatered and needs more? Instead everyone claims I need to adjust the 10 different settings in each of my 7 zones and hope I get them just perfect so that my “smart” sprinkler controller will provide the right amount of watering. I feel like I spend nearly as much time adjusting the settings on my rachio as when I didn’t have a controller at all and just had a set of sprinklers connected to my garden hose and drug it around the yard every time I felt like the grass needed watering.


I think maybe the crop evapotranspiration is what needs to be automatically adjusted for temperature to help with this.

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If you want to simply tell the Rachio that the ground is wet or dry you can fill/drain a zone. But that’s manual and a one time acuity.

You said you are using a personal weather station 2 miles from your house. Have you tried changing to using the “weather network” option vs the one individual station? I only say that because PWS can be highly inaccurate depending on the placement of the station and any user settings. Unless you know the owner and monitor his station results to other stations, it’s an awful lot of trust you are putting in to them. Their station essentially dictates when your lawn gets watered.

All the settings could be replaced by a slider for run time and a slider for frequency. Bizarre contradictory settings page.

I agree with all of these suggestions. The problem is that this is literally what I have already been doing for the past 4 years. While it is hot have been extending durations and telling the app that the water is “empty” in certain zones that it will water them more frequently. Then when it cools down, I have been skipping watering days. The whole purpose of the rachio is a smart watering system that you don’t have to constantly adjust. It just isn’t doing that for me. I have to constantly tinker with it in order to get the right amount of water.
As for using a PWS that is close to me, I admit that might be an area of concern, except that I checked aggregate data from all surrounding weather stations and for all data points (temp, wind, rainfall, etc) it was within normal variances.

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I can understand your frustration, although this hasn’t happened to me. It /sounds/ like you’re watering the same amount all the time, and not using Flex Daily, but you are. Can you please post a graph and table for a typical one, preferably over a 2 week period (2 screen captures)? Wish you’d posted during the hot period so we’d have that one to compare. And if you don’t mind, maybe post the typical values for your zones? There’s gotta be a hint as to the problem somewhere.

Just understand that the locally selected PWS is only used for Rainfall (which is extremely important and varies a lot from area to area), and not for any other variables such as temperature, humidity, etc. So as long as the PWS has rainfall close to yours, you should be good there.


Here are a few screenshots of the watering schedules over the next week or so. As well as the water tables for one area over the next two weeks. I would say that right now, when the weather is in the mid 70s- mid 80s, the watering schedule is perfect. Any hotter however and the areas in the sun don’t get enough water. Any colder, and all of the areas are over-watered.

Thanks. The depletion tables is what I was referring to. Could you post the tales you get while looking at the graphs and hitting the More Detail link? Another question: Do you have any restrictions on what days you can water?

Ok. Try these.

Okay, thanks. Just thinking out loud here, please bear with me: So, for the seven days 10/1 to 10/7 your ET values total 0.74". Mine, in Columbia, SC, vary more than yours, but add up to 0.78". They sound about right. Your system, for this zone, is putting down 0.47" per watering (mine’s 0.51"). With no rain, your system, at this time of year, should run every 0.74/0.47 = 1.57 times per week or every 4.5 days on average. Mine’s about the same. And you say it’s running about right now. So it really seems like your system is set up properly.

Now, in the summer, my total ET for the week will be at least double what it is now, meaning my system will water about every 2.3 days, if there is no rain. And that keeps my lawn happy, and yours /should/ be close to the same. All that sounds fine, to me.

But you say you’re growing mushrooms this time of year, with overwatering. Yet, I would think your lawn would dry out sufficiently in 4-5 days at this time of year. That’s not happening? I can understand getting rain and having too much water, but wouldn’t think that soaking the ground every 4-5 days would keep it that damp.

What is the Crop Coefficient for your grass? If that is low, it would result in underwatering, which would be most noticeable in the summer. You also mention your shade areas not drying out in the summer. It may be that the shade is much denser than Rachio’s Mostly Shade (2 hours of sun) allows for. Lowering the CC for that zone might help accommodate that. If, during the same weather, one zone stays damper or dryer than another, then changing the CC would help to equalize them. I realize it’s the same crop, but if the result is too little or too much water, then that’s a good way to adjust it.

I might as well ask how you determined the Nozzle Inches per Hour for each zone? Using the constant supplied by the program isn’t always best. I have the same sprinkler heads everywhere, yet mine vary about 2:1 from one zone to another. That can certainly be a contributing factor.

I realize you’ve been at this for a long time, so you can’t be /that/ far off, and probably especially hot or cool weather takes you over the edge. I’m sure you can fine tune it, and I’ll try to help.