Crop Coefficients, Basic Flex, Advanced

[franz]

@883

I have read a great deal about crop coefficients etc. It seems that what is “ideal” for one month might not be for another and so things are generally averaged. In my case I must average things for late April-October (anything else, my sprinkler lines are blown out).

Correct, they fluctuate based on time of year.

These are the values we previously used to dynamically change throughout the year. We do not do this any more and use the user adjustable value in Zone Advanced settings.

CROP_COOL_SEASON_GRASS, JANUARY, .61
CROP_COOL_SEASON_GRASS, FEBRUARY, .69
CROP_COOL_SEASON_GRASS, MARCH, .77
CROP_COOL_SEASON_GRASS, APRIL, .84
CROP_COOL_SEASON_GRASS, MAY, .90
CROP_COOL_SEASON_GRASS, JUNE, .93
CROP_COOL_SEASON_GRASS, JULY, .93
CROP_COOL_SEASON_GRASS, AUGUST, .89
CROP_COOL_SEASON_GRASS, SEPTEMBER, .83
CROP_COOL_SEASON_GRASS, OCTOBER, .75
CROP_COOL_SEASON_GRASS, NOVEMBER, .67
CROP_COOL_SEASON_GRASS, DECEMBER, .59

CROP_WARM_SEASON_GRASS, JANUARY, .52
CROP_WARM_SEASON_GRASS, FEBRUARY, .64
CROP_WARM_SEASON_GRASS, MARCH, .70
CROP_WARM_SEASON_GRASS, APRIL, .73
CROP_WARM_SEASON_GRASS, MAY, .73
CROP_WARM_SEASON_GRASS, JUNE, .71
CROP_WARM_SEASON_GRASS, JULY, .69
CROP_WARM_SEASON_GRASS, AUGUST, .67
CROP_WARM_SEASON_GRASS, SEPTEMBER, .64
CROP_WARM_SEASON_GRASS, OCTOBER, .60
CROP_WARM_SEASON_GRASS, NOVEMBER, .57
CROP_WARM_SEASON_GRASS, DECEMBER, .53

@883

In the post I linked to, you mentioned that with a flex schedule, the “Advanced” settings for crop coefficient are ignored. Is this still true? I run a basic flex daily schedule and have noticed that when I change the crop coefficient, I noticed that it does change the soil moisture (and therefore the watering frequency).

This is not correct. Crop coefficient values are absolutely used in “discounting” the raw evapotranspiration (ET) for the day.

@883

In that post, you noted different crop coefficients for different months. Does the Rachio include these adjustments automatically when running the basic flex daily schedule?

No, we used to but wanted to give user’s access to that value. At some point we might have the option to adjust automatically.

@883

Right now, it is certainly keeping the lawn green, but after I adjusted the crop coefficient to .87 (thinking it to be a reasonable average for the months I run), it seems to run quite a lot even when the temperatures are not particularly high (65-78 degrees). I have not kept up on the software changes of the last couple years where this matter is concerned.

In Colorado since we have cool season grass what I do is in cooler months (May/June/September/October) I will usually have it about 5%-10% lower (i.e. 70%-75%) than our default of 80%. I’ll adjust back up to 80% in July/August.

It’s by far the easiest lever to affect frequency since it doesn’t adjust watering durations.

Please let me know if you have any other questions, these are all great.