I have shrubs a in low depth of 12". But, Rachio suggests 15" as Root Depth for shrubs. Should I punch in 15" or 12" in the Root Depth box?
Are you saying that you’ve measured the actual roots?
I haven’t. I’m just wondering if it is reasonable to have 15" in my Root Depth box when my lawn is only 12" deep in total.
Sorry I’m a bit confused, could be the lack of sleep. When you say “root depth box”, are you referring to where you input the root length in the Rachio software? Or do you have some kind of real box?? 
And you have your grass set at 12" root depth? What type of grasss do you have?
Yes, I meant the box in the Rachio app. I have a couple of 3 feet Bougainvilleas in my lawn where my lawn is only 12 inches deep. If I consider them as shrubs, the Root Depth default value would be 15", which is even 3" longer than my lawn depth and it doesn’t make sense. So, I’m asking which number I should go for as my Root Depth: 12" or 15"?
Ok, so are they getting basically getting watered by the grass sprinklers also? So they are on a drip and getting sprinkler water?
I live in southern California and have a 2 Bougainvilleas, 5 Star Jasmines, 4 African Irises, one Cypress, one Morning Glory and one some tree, in a 320 sqft and 12" deep lawn. There 9 fixed spray head sprinklers evenly distributed. I’m trying to find the best flex configuration to not over/under water my lawn.
When you say 12" deep lawn, are you referring to the soil depth or root depth? Grass roots will be less than all of the other landscape plants.
And you have a lot of different plant types including grass. All of those root depths are different. You will have to fine tune that zone until the water duration works for the environment. Or just make it a bed zone without considering grass. It would seem that shade from the landscape plants would eventually prevent healthy grass growth.
Increasing and decreasing root depth will effect the zone run times.
1 Like
Sprinkleman is correct. Adjusting root depth keeps the water per week the same, but increases frequency of less water to account for the shorter time to 50% dry soil at the shorter root depth. This is the reason it is hard to have healthy trees and grass on the same circuit.
Sprinklerman, my lawn soil depth is 12".
The root depth of your lawn will be shorter than 12", likely 6". If the shrubs are in that zone, you will need to use 6" (the weakest link) which defines the frequency of the zone. The moisture per week (total time) stays the same with changing root depth for a fixed crop coefficient. If adjustments are needed, change the heads on the shrubs if you can to change the inches per week to what is needed.