Fine Tuning Flex Daily

Hi, I’ve had my system for about a month and have all of my zones set up on Flex Daily with every recommended setting enabled (smart cycle, freeze / wind skip, end before sunrise, start after sunset) I even went with Rachio’s recommended watering durations for each zone. I’ve been monitoring it pretty closely and have an issue that I want to fix but I don’t know how to fix it.

Even as the days grow cooler, the watering frequency seems to be increasing. When I first set up my Flex Daily schedules about a month ago the temperatures outside were consistently mid to upper nineties. Now they are consistently in the high eighties, yet the Rachio system seems to want to water every other day now, whereas previously it was watering every three days; I haven’t changed any settings at all. Before I set up my Rachio system I would water for 15 minutes every three days with a nice result in my lawn, now the Rachio waters every two days for 28 minutes. The lawn isn’t any greener, but it is growing much faster which means more mowing of course. I can just decrease the watering duration back to 15 minutes, but won’t that make the system water even more frequently?

I’m on a Rachio 3, BTW

1 Like

Think of your flex program as a whole pie. Your yards needs that “Whole Pie” every week.

If you slice the pie in 3 pieces (watering 3 days a week), you are still applying the whole pie. With 2 slices (watering twice a week), you are still dealing with the “Whole Pie” but in bigger slices. (longer run times)

As the ET values increase (bigger pie) you are still using a whole pie for the week but not it is a bigger pie.

The same thing happens with your irrigation requirements. The Rachio calculates how much water is required on your landscape. As evaporation increases, more water is needed. A decrease, obviously requires less. (Big pie or smaller pie)

Different factors increase or decrease the ET valvues, Heat, Wind, cold and rainfall.

The best health of your landscape requires deep and infrequent irrigating.

@omatase @spscoutenPhD did a great job of covering the concepts of flex daily.

Your projected graph for next week looks close to every three days. It will dynamically adjust based on evapotranspiration values.

To decrease frequency I would adjust the zone crop coefficient down by 5-10%. It is currently set to 80%. I would try 70-75%. This will tell our system the yard is burning moisture slower. This should help understand the levers that adjust flex daily.

Hope this helps.


1 Like

So are you saying that if I decrease the duration of the different zones in my schedule, the Rachio system will just increase the frequency of the watering? I want to add that after decreasing the watering by about 1/2 I still have grass that is just as green as before, but it doesn’t grow nearly as fast. Rather than having to mow every 6 days, now I don’t have to mow but once every 3 or 4 weeks.

BTW, what does ET stand for?

Flex daily schedule frequencies do not change when you adjust watering duration.

Do you want to decrease watering frequency?

ET stands for evapotranspiration. I just found this blast from the past.


OK, so if the watering frequency doesn’t increase based on my duration, then taking that to an extreme if the Rachio system would water every three days with the duration set at 30 minutes and I change that duration to 1 minute, it will still water every three days?

Does the Rachio system just expect that once a watering has taken place at the duration I have set, that the saturation for the soil is at the ideal level of saturation after a watering? Does it assume that the soil saturation is, say, 60% (just picked a number) whether it watered for 30 minutes or 1 minute?

I’m just trying to pin down how it works so I know how to adjust my scheduling or watering durations. I assume if it’s attempting to track ET, then it determines the soil is ideally saturated after a watering, because if it attempted to determine soil saturation and by extension ET based solely on soil type, temperature and other knowable factors in the watering it would seem that it would also need to guess what the soil saturation is based on the volume of water sprayed in a single watering and if it did that, I would expect the frequency to increase when the duration decreases and vice versa.

For flex daily we make the assumption that the current duration fills your soil moisture bucket. There are various reasons we need to make that assumption based on how the watering algorithms work. The duration does not affect frequency.


We derive the optimal duration based on user input variables (e.g. nozzle, crop, soil, MAD) and assume that fills the bucket to depth of water (field capacity). If the user changes the duration we still have to make that assumption or how we determine watering frequency breaks down.

Great questions!


OK, awesome, that helps me understand what I needed to know.

Thank you!

Does Rachio also assume the same after rainfall? Does it fill the “soil moisture bucket”?

Precipitation is tracked exactly like irrigation, it increases the soil moisture level.

This graph has an example of precipitation being tracked.