Dry winter

Rain is seriously lacking right now in Northern California. Thus Flex Daily is about to irrigate. That’s good! Bone dry roots in general are bad and citrus evapotranspiration coefficients do not change much over the seasons. Glad Flex Daily is keeping track of this for me.



@Kubisuro, virtual rear lawn?


@tmcgahey, is that a picture of what he wished it looked like?

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It’s my Minecraft lawn.

Actually it’s an unconnected zone that lets me know when to turn on my oscillating sprinkler (hose bib, no auto valve).


Would you mind sharing your configuration (Available Water, Root Depth, Crop Coefficient, etc.)? Because I’m also in NorCal and I’ve been having a miserable time tweaking mine to do sane for my garden, which includes citrus and stone fruit. E.g., it wasn’t watering enough in the summer, too much in the winter, to the point I put it in standby in November when it was watering needlessly.

Well, one group of settings doesn’t fit every circumstance. I use 1 GPH emitters and have calculated the in/hr based on the the average tree drip line radius for the area in the in/hr calc. Also, stone fruit evapotranspiration changes throughout the year. Peak summer in NorCal could be near 100%, while in the winter you could go down to 40% or less! That low of an ETc in the winter has huge ramifications for water frequency. I actively manage my settings, based on the time of the year and tree response. I’ve never found a perfect setting, made harder by the fact the trees continue to grow or get infested by metallic wood boring beetles doing their best to girdle my cherry tree… SCREAM. I’ve set root depth to 12" for my stone fruits and citrus. A recently planted very young nectarine is on the Garden zone, watering to 8" depth for a much much shorter period of time than the mature trees. I learned a hard lesson last year and that was not to put a new tree on the same zone as adult trees. Instant root rot.

Citrus, on the other hand, has crop evapotranspiration between 70-80% all year! So it’s safe to just keep them at one value throughout the year. Or so I have found.

So here’s the two resources I suggest for in/hr and evapotranspiration:

Evapotranspiration – You’ll need to divide the value given for your tree during a certain month (selected from a dry, normal or wet year) by the grass reference ET0


Note that putting Rachio in Standby still allows Rachio to calculate ET so you can monitor it during a dry spell and determine if you need to bring the Rachio out of standby. Of course, that’s also a great time to compare its model to how dry the soil actually is.

Hope this somehow helps. Sorry I cannot provide advice to make for perfect irrigation of trees.

One thing to be aware of with the evapotranspiration PDF – for nectarines, peaches and apricots in December and January you’ll find that the trees have the same ET as ET0… which calculates to 100% if you do the math. Critically thinking, that’s not right. Beats me why though in most cases we’ve got enough rain those months to make irrigation not necessary at all. So I use the 40% or less value calculated from February or November until Spring. :man_shrugging: Far far better than keeping it at 80-90% year-round!