Plant coefficient question


What value does the plant coefficient effect? I would guess ET.

Also, are there plans on allowing custom vegetation types because if the value modified is ET, then .3 for succulents is way too high for cacti.


Hi @nillooo13, good evening.

Great question. The plant coefficient is a key variable used in determining evapotranspiration (ET). There may be several crop coefficients used for a single crop throughout an irrigation season depending on the crop’s stage of development. We account for this in our schedule recommendations. In short, the higher the coefficient number, the more water the plant uses.

The coefficients listed for each vegetation types listed are averages assumed by the EPA. We’ve considered allowing for custom vegetation types (it’s a great idea btw) but how or when we’ll support this is TBD at this time.

What custom vegetation types would you recommend adding?

Best, Emil


I think the vegetation types are fundamentally flawed because plants in the type shrub can have coefficients from .9 to .1. The same holds true for say cool season grass with turf fescues to mexican feather grass. So you are left with just picking the coefficient closest to what the zone really needs when all you really need is a slider. That slider would then allow you to adjust the coefficient during the course of the year to account for summer dormancy.

Then there is the issue of control of water use. Most plants don’t have one coefficient. They have a range. So one plant might love to be supplied with water at a coefficient of .6 but if necessary it could survive at a .3. By being able to adjust the coefficient you could precisely dial back water use.


@nillooo13 Thanks for the feedback. In future updates we are going to expose things like crop coefficient so that you can ultimately configure similar to our custom nozzle library. It’s on the road map, but probably won’t show up for quite some time.