Flex Daily - New Beds

I have brand new landscaping, and have been doing all the math to get my advanced settings just right. The suggested watering times for my lawn seem to make sense, but when it comes to my flower beds, my rachio gen 3 is suggesting 2-3 hours per bed which doesn’t seem right.

I pulled the GPM for each of my Hunter MP rotors that are in the beds and used the formula provided on another thread of (96.25 x Ttl_GPM)/Area to get my nozzle inches per hour. I have the root depth set at 10" since it’s a mixture of larger and smaller plants. Otherwise, the rest of the settings are default. Any suggestions?

Area: 820 sq ft
Available Water: .17 in
Root Depth: 10"
Allowed Depletion: 50%
Efficiency: 80%
Crop Coefficient: 50%
Nozzle inches per hour: .37 in

Zone Type: shrubs
Spray head: rotary nozzle
Soil type: loam
Exposure: lots of shade
Slope: flat

Any suggestions?

Published GPM for rotors depends on a lot of variables, like pressure, etc. If possible, it would be better to measure ACTUAL GPM used on the zone, normally using the water meter. Just take a reading, water for maybe 10 minutes, take another reading, subtract for the total gallons used, and divide in this case by 10 minutes for GPM.

Other than that, it does sound about right. Based on the above, for Flex Daily Rachio will try to apply 0.17 x 10 x 0.50 = 0.85" each time it waters, which will take about 0.85 / 0.37 / (0.4 + .6 x .80) = 2.61 hours, so the math is right. Flex Daily in your case won’t water often at this time, though: I’m running a ET of about 0.52" per week in Columbia, SC, with 85% CC. With 50% that would be 0.306" per week, so you’ll only water every 19.45 days. Of course in summer here, it might approach 3 times as often, or every 6 days.

That, to me, doesn’t sound often enough, depending on root depth, how new plantings are, etc. In my experience, you should use the shallowest root depth, because that results in watering less water at a time, but more often. Halving the depth to 5", for example, would water only 0.42" at a time, taking 1.3 hours, but watering twice as often. I think that might be better.

Root depth is important, but deep root depth just means the plant can go a long time between watering, for 50% AD, and has to take a lot of water at once. As long as the soil starts out saturated, it will have water at the deeper roots. Then the shallower roots can still dry out as they should, but get watered more often. Flowers in particular normally have shallow roots, and those are the ones you should be basing the schedule on, IMHO.

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I agree with @rraisley. This seems pretty close. My drip beds use mostly 1/2gph emitters, so I ended up setting my nozzle inches per hour to .2. My beds are a mix of perennial and annuals, so I basically set for the annuals with a root depth of 7 inches. A bit of a compromise between the two. And I also set my allowed depletion to 25%. I found that if I didn’t do that, sometimes my annuals would start to droop. So with those settings, my system runs each zone for 74 minutes. I’ve tweaked it slightly over the last 3-4 years, but have found it’s working pretty darn well. Didn’t mess with it at all this year, and the plants looked good all summer, even in the really hot weather here in NC. In the hottest weather it watered every day, and sometimes every other day. And the plants all did well.