Help setting up watering for a zone of trees and roses using drip emitters

I’m trying to figure out the watering for one of my zones. It’s supposed to rain a lot every day for the next 2 weeks, so this is more preparing for after this series of storms is done and I need to water my plants. Where I live in south GA, we have no watering restrictions, and we’re on a deep well so negligible cost for the electricity to run the pump.

I have a zone that covers

  • A cherry blossom tree that I planted last month (maybe 7-8ft tall and 3ft in diameter)
  • 2 rose bushes just planted (about 3ft tall)
  • A banana tree (about 5ft tall)
  • 2 crepe myrtles that were just planted (maybe 3ft tall each)
  • A shrimp tree just planted (about 2ft tall)
  • A Rose of Sharon (about 2ft tall)

All of them have drip emitters placed in the ground using Deep Drip Watering Stakes, with the emitters about halfway down the stakes. Currently, but more than willing to change:

  • The 2 rose bushes have 1x 2gph emitters in a 8" stake each
  • The Rose of Sharon has 1x 2gph emitter in a 8" stake
  • The banana tree has 1x 2gph in a 14" stake
  • The 2 crepe myrtles have 1x 2gph emitters in a 8" stake each
  • The shrimp tree has 1x 2gph emitters in a 8" stake each
  • The cherry blossom tree has 1x 4gph in 14" stake and 2x 4gph in 24" stakes.

Does this seem reasonable? My dad said they need lots of water when starting out, but right now we’re getting over 1/2" of rain every day, so pretty sure that’s covered, lol. Tried setting up a Flex Daily schedule and it wants to water like once a week for 3 minutes each time, so I know something’s screwed up in my settings there, lol. The current settings for this zone are below. I set the soil type based on some government site I found that said we have Loamy Sand, but all of these plants have been planted in a 2 cu ft bag of either garden or potting soil (can’t remember which we used), except the cherry blossom tree that got 2 bags of soil.

  • Vegetation Type: Trees
  • Spray Head: Emitter
  • Soil Type: Loamy Sand
  • Exposure: Lots of sun
  • Slope: Flat
  • Area: 427.8 sq feet (from the Yard Map)
  • Available Water: 0.07 in/in
  • Root Depth: 12 in
  • Allowed Depletion: 50%
  • Efficiency: 100%
  • Crop Coefficient: Dynamic, May, 54%
  • Nozzle Inches Per Hour: 8in (this was a shot in the dark)

As I said, won’t be watering for at least 2 weeks now with the weather, so plenty of time to figure out what settings I need to actually use and how often to water.

Messing around with ChatGPT gives this set of calculations for converting 12gph for the Cherry Blossom Tree to in/hr. Does this seem right? I get 0.0675 in/hr average for my current setup, though it says for everything except the Cherry Blossom Tree that I need to double the number of emitters for them, giving a new value of 0.1195 in/hr

Initial Calculation:


Here, we’re dividing the flow rate (in gallons per hour, gph) of the Cherry Blossom Tree (12gph) by the total area covered by its emitters (25 square feet).
12 gph represents the total flow rate for the Cherry Blossom Tree.
25 sq ft represents the total area covered by the emitters for the Cherry Blossom Tree.

Dividing these gives us the flow rate per square foot: 0.48 gph/sq ft

Conversion to Inches per Hour:


Here, we’re converting the flow rate from gallons per hour per square foot to inches per hour.
1 inch/231 gallons represents the conversion factor from gallons to inches. This factor is derived from the fact that 1 gallon is approximately equal to 231 cubic inches.
60 minutes/1 hour​ represents the conversion factor from hours to minutes.

Multiplying these factors by 0.48 gph/sq ft gives us the flow rate in inches per hour: 0.124in/hr (approximately).

This calculation tells us that the Cherry Blossom Tree’s emitters deliver water at a rate of approximately 0.124 in/hr to each square foot of the area covered by the emitters. This helps in determining how long to run the irrigation system to deliver a certain amount of water to the plants.

You’ll do the same calculation for each plant and take an average for the whole zone.

I haven’t had a chance to really review your 2 posts, but quick scan, the biggest issues I see is that you have vegetation types with DRASTICALLY different watering needs on the same zone, which makes things a bit more tricky. If you set the zone up as a “tree” zone, I guarantee that your roses, and most likely the banana tree are going to suffer. Both those are going to need more frequent watering than a properly set up “tree” zone is going to do, assuming you follow the cherry blossom and crepe myrtle needs.

As for nozzle inches per hour, 8in is WAY off. Your emitter package isn’t far off from mine (I’m a little above and a little below depending on the zone), and the calculations come back at around .35"-.65"/hr

How do you calculate in/hr from gph of your emitters? I found this here watering - How to convert inches to gallons? - Gardening & Landscaping Stack Exchange which says to essentially add up the gph of all emitters, convert to gpm, then plug into the formula (96.25 * gpm)\area. So my current zone (I know it’s probably not balanced well, but just for the sake of understanding the math) has a total gph of 26 and area of around 95.

26gph \ 60 = 0.433gpm
(96.25 * 0.433) / 95 = 0.439 in/hr

Does that math seem right?
Also, I did change up the zone some since the bug post, moving the spray heads from this zone. Both zones are drip irrigation lines, with the spray heads being those little red/blue 90/180 deg sprays. All sprayers are on the other zone and those are mostly pots which we’ll run once to twice a day to keep the soil in the pots damp, adjust the flow of each nozzle so they are all about the same dampness.

So how does this sound for more realistic Zone settings:

  • Soil: Sandy Loam (cuz of the use of garden soil in the holes dug)
  • Area: 90 sq ft (25 for the Cherry Blossom Tree + 10 for each of the other plants)
  • Available Water: 0.12 in/in
  • Root Depth: 12 in
  • Allowed Depletion: 40%
  • Efficiency: 100%
  • Crop Coefficient: 85%
  • Nozzle In/hr: 0.439 in with current setup (3x 4gph on Cherry, 1x 2gph per each of the others, total 26 gph, though 0.12 seemed to give more realistic water times)

Banana tree: We planted it last summer, unlike the rest of the stuff that was planted a month ago. Reading online, can’t find any articles that actually agree with each other about how much to water them, but the most realistic (as far as I can tell), says 6-8 inches per week at first and then just “every 2 weeks” once it’s established and more start popping up around the first.

Roses: I read online that they also do good with once a week watering to promote deep roots (How to Properly Water Roses: 14 Steps (with Pictures) - wikiHow), though may be more often in hot enviroments. With more reasonable numbers in the Advanced Settings for this zone, Rachio is wanting to water closer to every 2-4 days depending on the in/hr setting I put in.

So if they all can handle weekly/twice weekly watering to encourage hardier deep roots, then it’s a matter of balancing out the number of emitters and the gph to use per plant, so they can all be watered about the same total time.

Does this seem like more reasonable amounts:

  • Cherry Tree: 3x 4gph
  • Rose Bush (2): 2x 2gph
  • Banana Tree: 2x 4gph
  • Crepe Myrtle (2): 1x 2gph
  • Shrimp Tree: 1x 2gph
  • Rose of Sharon: 2x 2gph

And then tweak the in/hr so that it runs around 4-5hrs per session, for twice a week?

This excel file that one of the community members put together is the best tool for that. The problem you are going to run into is your rather large range of vegetation on the zone (I think your other post even eluded to mixed irrigation types on some zones). @azdavidr did a great job detailing how to fill out the calculator, but if you need any additional help, report back.

But, understanding that 3.5-4 hours is “normal”, and letting Flex daily handle the frequency, you’ll be in a pretty good spot. Only thing I can see from there is that you may or may not need to adjust individual plant emitter setup slightly if you find something needs a bit more/less water.