I finished my installation and set up using Gen2 controller and mostly Flexible Monthly Schedules last January. I found lots of useful tips here from others who have struggled with a drip setup but hardly anything comprehensible from Rachio. So I devised my own approach which, some months later, seems to be working well.
I need to start by saying that I began with an existing baseline provided by an earlier
Weathertrak unit… and this baseline was if not optimal at least working… in other words at any given time I knew how much water was being delivered, zone by zone, in the current month. Since my plants looked pretty good, I decided to set the Rachio so it duplicated what I had knowing that if I told it what was needed in January, it would adjust the Flex monthly and daily programs to provide what would be needed in the following months.
If you are starting from scratch and have no idea what your zones actually need, what follows won’t be very helpful.
Before tossing my older system I recorded what it told me it was going to do that month. So in Zone 1 I learned that it was going to run 7 times for 6 minutes (42 total minutes) on Jan 1 then again on Jan 18. Dividing 42 minutes by 18 days told me it expected to deliver 2.33 minutes of water per day in January to Zone 1. Because my former system seemed to be delivering about the right amount of water, I used this as my baseline. (Caution, if you do this, you will get a number which is only valid for a few days, in my case for the month of January. If you wait a month to enter this data, Rachio will assume this baseline is what you want in February…wrong!)
I mostly used the Rachio default settings to begin but set a custom nozzle size in each zone, saved it, and calculated that zone’s run time. I also selected Flexible Monthly as my scheduling choice. Lets say for discussion purposes that I set the drip emitter custom nozzle size at 1 (compared to the 1.6 Rachio assumes for its emitter.) After running the schedule, I learned that Rachio would operate this zone twice in January 23 days apart and deliver 19 minutes of water each time… in other words at that custom nozzle setting the system thought it needed to deliver 19/23 = 0.82 minutes of water per day… way lower than my old Weathertrak data said I needed. To increase the amount of water delivered, I returned to the Rachio zone description, decreased the custom nozzle size to 0.7, and ran a new schedule. This time Rachio said it would deliver 38 minutes of water each 23 days, or 38/23 =1.65 minutes per day. This was much closer to my target but still low, so I reduced the custom nozzle setting to 0.4. This time Rachio calculated that it would deliver 51 minutes of water over the same 23 days. Now I was in the ballpark… 51/23 = 2.21 minutes per day…very close to my Weathertrak baseline. In other words, the Rachio was now going to deliver about the same amount of water as my Weathertrak in January.
This sounds awkward but after you’ve done a zone and fooled with the different nozzle sizes to get the result you want, you get pretty good at quickly guessing what the custom emitter nozzle size ought to be. Subequent zones can be calculated the same way very quickly.
While doing my settings, I decided to be very conservative and to set the custom nozzles to deliver 20% more water than they had been previously… i wanted to err on the side of being extra wet to start rather than extra dry. So I reduced the nozzle size a small amount to increase the duration of each watering about 20%. (Using the same example, I set the nozzle size to deliver about 2.21 + .44 = 2.65 minutes per day of water.)
In the months since my initial setup, Rachio has calculated new watering durations and timing each month, gradually adding water each month as we moved into summer.
As others have noticed, Rachio doesn’t cope well with a zone containing a citrus tree or other heavy water user and several other well established plants with much smaller needs. My advice is to add a drip emitter or two to the plants needing a lot of water, change the emitter size from 1gph to 2gph there, and tune the zone to meet the needs of the heavy users. This may mean that the non-heavy-users will get a bit more water than they need, but at least everything will still be alive! If you’re willing to fool with this a bit over a weather cycle, you should be able to get pretty close to optimal watering.
Over the course of about six months, my technique has worked pretty well. I have made small changes to the nozzle sizes in 3 of my ten zones, adding or subtracting water as suggested by occasional checks to soil dampness near plant roots or simply eyeballing the zone for signs of stress. In one zone, which happened to contain both newly planted citrus and other better established less-thirsty plants, I raised the plant coefficient default setting from 50% to 75% to reduce the interval between waterings. Other than that, my initial settings have worked well.
You’ll notice that there is no calculating of gallons per hour etc. If you know that your plants are happy today receiving 52 minutes of water per month, and you set the Rachio zone to accomplish that this month, you’re set! And two months from now, when it’s warmer or colder than today, the system will compensate for that… assuming of course you are using Flexible Monthly or Daily watering.