When I first read your post I was surprised as well but considering my tomato plant is almost as tall as me know it makes sense for it have roots that deep. I think I’m going to try setting the coefficient to 100% then make adjustments in the flex schedule, increasing the time by 15%. I think that should be close to simulating a crop coefficient of 1.15. I’ll see what I get later when I have time today and post the results.
Thinking about this some more increasing the time it waters wouldn’t simulate anything as far as crop coefficient goes since the coefficient affects frequency of watering and not length of watering I think. I’ll have to think about this some more.
@franz - since ETo is just a baseline number, is there a reason actual ETc couldn’t be higher or lower than that? I thought that the crop coefficient just related the actual evapotranspiration of a particular plant to that baseline. I was assuming some plants use more water than that and others less.
@cwiedmann Great question, going to have to wait on someone with more knowledge than me in this domain to chime in… 
@franz I am by no means an expert. In fact, I’m pretty new to all of this and am learning on a daily basis thanks to these forums. However, I found this an intriguing topic as I have a garden as well and have been wanting to play with the newly exposed crop coefficient. I found a couple of articles that reference Kc values greater than 1. Just FYI, take it for whatever you think it’s worth.
@azdavidr Oh thanks for this, love learning new things. I’ll be sure to put this in our backlog. Very interesting.
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Hi Franz, does the crop coefficient change change each month for “perennials”?
With current flex schedules, we do not adjust crop coefficient from month-to-month for any crop types.
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Crop coefficients never change. However, ET determines when and how much to water each specific plant type.
I think this is how the Rachio Iro 2 works:
I believe Rachio’s end of the day calculation for actual Crop Evapotranspiration comes from obtaining a reference actual evapotranspiration value in some manner and then multiplying it by the crop co-efficient we put in to each zone’s input parameters (via specifying a plant type).
I;m uncertain where Rachio’s reference actual evapotranspiration comes from. Hopefully it’s a function of the day’s temperature, cloudiness, solar radiation, and wind data obtained from the weather station I’m connected to, the soil type I put in to each zone’s input parameters, and a reference short grass plant type.
I believe Rachio’s reference actual evapotranspiration makes the assumption that soil moisture was between 50 and 100% saturation.
Best regards,
Bill
Exactly.
Yes!
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I’m curious if the coefficients and functionality stated in this thread are still the same. I started investigating because I thought I had my system dialed in until a series of temps >90 this last week have started to stress my Kentucky Bluegrass. I’ve been able to revive it with supplemental manual waterings but would like to get it figured out. I noticed my coefficients are currently set to 0.7 and thinking they should be higher based on the post here.
Hey @vnephologist-
The only changes that were made to cop coefficients after this thread was we set the maximum crop coefficient to 1.5 for things like tomatoes. You can adjust your coefficient for your grass if you think your system is not watering frequently enough!
McKynzee