Drip emitter sizing?


Inherited drip irrigation that looks like they defaulted to 1/2 GPH emitters for everything, whatever the size of plant.

I would like to fix things so I can truly let Tachio take care of things.

How do I go about figuring out the size of the emitter required for small/medium/large plants & bushes along with trees? Speaking of trees, I can’t find any definitive source to say how many gallons they need per week (weeping cherry/redbud/dogwood/arborvitae). They were all planted a year ago.

Many thanks.

This table was done by an Arizona based group “Water Use it Wisely”, but can be used anywhere to dial in needs of plants. Not all plants are going to follow this exactly as some are more water hogs than others, but it is a great baseline. If each shrub and tree only has 1 emitter running to it, you might struggle to get each plant the water it needs. How hard would it be to run an additional emitter hose or two to each larger tree?


Thanks, that’s very helpful!

I’m guessing that someone somewhere has documented the needs of individual plants - wish I could find it!

Once the right emitters are sized, how does Rachio adjust watering time based on weather?



Possible that this exists SOMEWHERE out there…but that would be a lot to weed through!


If you want simple, just set up fixed schedules and it will skip watering based on rainfall, wind, freeze, whatever options you choose, but it will be a fixed schedule set up by you.

Then you have the Flex schedules, with Flex Daily being the most powerful. That schedule is a fully dynamic, always changing/adjusting based on a number of weather factors. IMHO, it is the best schedule option Rachio has, but it takes some effort to set the zones up correctly so that Rachio has the information it needs to work correctly.

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This paragraph should be pinned at the top of the Community board.


But adjustable emitters – that way you can have one type but scale the flow for the plant’s size. Increase the flow as plants grow.

Personally, I hate the adjustable. You have zero clue what flow rate you are actually getting on those. The better option is to increase the number of emitters or the gph of each going to the plant. As the plants grow, you can adjust with time as well.