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So with this scenario your best bet may be to use IFTTT. I am not sure if you are familiar with this but basically what you can do is create recipes (commands) for the Iro. So you could create one watering time with all of your zones that have seed and setup Google calendar events that will trigger this watering time to run. I can walk this through with you on the phone if you would like. Or if you want to email us at email@example.com I can email you the steps that you would need to do.
Let me know what works best.