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?