Super long watering time for shrubs in Phoenix


I just installed the Rachio today and the suggested watering times for my plants, shrubs etc. is 2.5 hours… witch I believe is way to much. I have 2 GPH drips.

The suggested watering times for the front and back lawns are good with 22 mins.

I don’t understand why it wants to run the drip system for 2.5 hours. Any information would be greatly appreciated!




Thanks for reaching out to us. We appreciate you joining the Rachio community.

That suggested duration does seem quite long. Would you be willing to email us at with your username and we will be sure to review and provide some insight.

Thanks again for your time.



@dthornburg84, good morning. Just following up on @kevinro’s post. I’d like to address a few questions on the community if you’re open to sharing with others that might benefit from your question.

Do you happen to know what nozzle types you had selected for this zone? The nozzle type plays a big role in your watering time durations as the precipitation rates determine how long the zone should run for. In your case, we probably just had a nozzle selected that didn’t match the actual nozzle type or output of the nozzle in your system.

Let me know your thoughts around this.

Best, Emil


Of course, feel free to add this to the community. I figured a 2 GPH drip emitter is a common type of emitter. I am still lost as to what flow rate on a custom nozzle I need to use for a 2 GPH drip. I got a response back from Kevin and he said it would be around 3.4 inch/per hour. So i input that into the nozzle and went to create a new water cycle time and the auto water cycle created drip times of 6 mins every 3 days which isn’t enough. If there was a way to figure out your inches of precipitation based off of a chart with common drip emitters and their respective flow types it would probably help a lot.(2 GPH, 5GPH etc.) Its just an idea and I thought I would run it by you guys.


@dthornburg84, sorry for any confusion on custom nozzles. For a 2 GPH drip emitter, a 1 square foot coverage (assuming drip line placement), the precip rate would be 3.21 in/hour.

I think it would help to step back and rethink the calculation. The precip rate (PR) is not the same as the flow rate. Let’s break down the equation for everyone to better understand:

PR = (96.25(A*B))/©

96.25 = constant that converts gallons per minute (GPM) to inches per hour. It is derived from 60 minutes per hour divided by 7.48 gallons per cubic foot. times 12 inches per foot.
A = #heads -or- #emitters
B = flow rate (GPM) per head -or- emitter
C = zone square footage

I hope this helps. For a detailed explanation, please reference this article

Love this idea! We’ll look into creating this…or better yet, a custom nozzle calculator :wink:


How about you have a little button switching to GPM instead, this is what is normal …


I saw the title of this thread and felt the need to respond. Shrub watering times in Phoenix should be super long. Take a look at this like for my experience, and references to our local watering guides.