Wouldn’t the following scenario, which is how the Flex Daily algorithm works, be detrimental to a lawn, especially a cool season lawn?
Day 0: MAD for a zone is configured at 50% and the current soil moisture is above that value but not by much.
Midnight: The forecase for tomorrow (day 1) is 100F (38C) with enough rain to bring the soil moisture to the field capacity.
In such case, the Flex Daily algorithm won’t water because of the forecasted rain.
But something that is not considered by the algorithm is the forecasted time (hour) of the rain, what if the rain is forecasted to begin only by the end of day 1?
So even in a perfect scenario that the forecast was accurate and the rain will bring the soil moisture to the field capacity, it still means that during almost 24 hours the lawn was below the allowed depletion level and most likely even reached 0% soil moisture.
Wouldn’t it be an issue for a cool season lawn, especially if being repeated during the season?
Not in my opinion. The 50% is a rather arbitrary value, and still means that half the water is available to the zone. A little over or under 50% really doesn’t matter much. The main thing is that if the forecast is right, then you’ll still be in good shape the following day. Hours one way or the other shouldn’t matter.
Not sure If I completely follow your scenario here, but I do believe that Rachio Flex Daily also checks 1 hour prior to scheduled watering time, and will adjust accordingly if the weather has changed.
Like @rraisley said though, the AD is somewhat of an arbitrary number, and a few extra hours of no water isn’t going to be the death of your grass. If the rain never comes on Day 1, Rachio will pick up and water on day 2.
reading this got me thinking of a this hypothetical scenario: every day a heavy rain is forecast but never comes. What would Rachio do?
Oh, btw, does anyone know if for forecasts Rachio is just looking rain or no rain or it is trying to work into its formulas the forecast precipitation rate?
As I understand it, Rachio will keep relying on the rain forecast and won’t schedule watering.
The forecast precipitation rate is used, you can see it in the Soil Moisture chart.
I can’t see it in the soil moisture chart because we won’t have another rain until December or so, but I’ll take your word for it
I remember some discussions on this in the past. It can be a problem here in the Carolina’s in the summer where we have a scattered shower forecast every afternoon and nobody knows who’s really going to get it. On rare occasions, I’ve forced a watering just to make sure things stay ok.
Those forecast showers usually have very little anticipated precipitation. Therefore, even if rain is anticipated, Rachio knows it won’t be much, so will go ahead and water. Flex Daily will only hold off watering if the scheduled rain is enough to eliminate the need for water.