I’m setting up a new schedule, I have no idea as to how often to water out Centipede Warm Season Grass. If I set a Zone to water Any Day, will it automatically skip unnecessary watering days and maybe just schedule to watering for 2 days after the first watering has occurred ?
Depends on the schedule. Yes, if you set up a Manual schedule to water every day, it will not water on days you get enough rain. But you’re dependent upon your settings to get the right amount of water. Plus, even for Centipede’s more shallow roots, watering every day is too often. I think it’s best to use Flex Daily, ALLOW it to water every day, but let it decide when and how often to water.
Thanks @rraisley for the reply,
My unit isn’t installed yet (it’s in Ireland), but my Weather Station is in place (it’s in Spain), so I’ve created a schedule to see how it “plans” to water, based on the local Spanish weather.
So I’ve started to play with the various parameters within each zone, to see the effect of one setting over another.
I know that the ground in Spain is clay. I measured the sprinklers in 2018 and they deliver aprox 10 litres per minute (we’ve 146 sprinklers across 14 zones). I’ve asked someone to try and find out the root depth. So I’m struggling a bit to relate some of these values to the Advanced parameters.
Does area matter other than maybe to calculate the water used or saved ?
We currently water on a fixed schedule, some 90,000 litres per week in the summer. I feel we over water so to even save 10% would be huge
Knowing your sprinkler output is extremely helpful in figuring out how to proceed, so that’s good. Is you 10 litres per minute for a single sprinkler head? Seems a bit high, but seems way low for a zone.
With 14 zones and 146 sprinklers, it sounds like a pretty large property you’re irrigating. With your current system (before Rachio), do you water all your zones in a single day?
I would definitely make up a table of how many minutes you are currently watering for each zone along with any notes such as whether the zone tends to be too dry or too moist. You have a LOT of water to waste or save, and you want it to be on the save side.
Root depth isn’t too critical; it helps determine, along with Allowed Depletion, how much water is applied at once. Deeper roots tend to require more water at one time, but applied less often. The opposite with shallower roots.
The main reason, IMHO, for measuring or calculating area is that it is an excellent way to determine how much water your grass/crop is getting at one time. You can calculate cm of water per week is being applied, and compare that to the FRET recommended values, of probably 1.5" per week in summer.
Basically, if you’re starting with a new system, you really want to know (but rarely do) how much water is being applied per hour to each zone. The best two methods are Catch Cups and Calculation, based on area and actual water usage per hour. If you can measure area, I think it’s the best way. OTOH, if you know how many minutes per week works with an existing system, you can start there.
Absolutely. Well, applying the right amount of water, not too little or to much, in order to keep a lawn green and healthy, can be hard to find, and usually results in trial and error.
I’m a little concerned about you being able to apply all that water with one controller. Can you clarify about the 10 l/min? Does your current system allow more than one zone to water at once? If it does, and if that is required, a single Rachio controller won’t do the job, as it only allows watering one zone at a time.
Zones are typically 9 to 12 sprinkler heads per zone. When I measured in 2018, running a zone for 2 mins used over 200 litres on most zones.
Irrigation has it’s own water feed and it’s own meter. Piping appears to be about 1.5" piping.
Currently, during the high summer, grass watering is on every second day and essentially alternated two blocks of 8 zones each day. Each zone is watered for 20 mins. No two zones were watered concurrently. Last year, during high season, we were consuming 91,000 litres per week.
Surely, even to water 16 zones separately for 20 mins each, the system would handle them fine as 3 periods per hour over 7 hours is 21 periods ?
We are in the lucky position where the Rachio unit will almost pay for itself if it rains about twice and stops watering from being carried out.
A question - if our PWS gets rain, does the Rachio then add that moisture to the levels of each zone, which would then push Watering on a day or two further ?
I knew this thread was familiar. Answering similar questions at the same time in two different threads is confusing to say the least.
Okay, that clarifies that the 10 l/m is for each head. Good to know. Zone flow is 100 l/m or over.
Good size system.
True enough, if you’re currently watering 20 minutes per zone every other day, you can water all 16 zones in 5.3 hours. That’s some high water flow!
That also checks out with your total of 91,000 liters per week: 91,000 ÷ 100 l/m ÷ 60 m/h = 15.17 hours per week, or around 5 every other day. Good. And from the other thread, you can water between 4 PM and 7 AM the following day. So a schedule ending at 7 AM would be perfect for you.
Depends on the schedule type. A Fixed or Flex Monthly will use Rain Skip if you’ve had a certain amount of rain recently. But won’t skip a second time if it was a lot of rain.
Flex Daily, which would certainly give you the most potential savings, will consider the irrigation water applied Plus any rain received, and calculate when to water. I would suggest that.
Your 20 minutes per zone sounds like the normal contractor suggestion, without really knowing or being able to calculate how much to really apply. But it’s worked for you, and is certainly a good starting point. I’d play with the Advanced settings (we can help with that) to give you close to the 20 minutes for each zone. Then make a change to reduce water everywhere by 10%, and check ALL zones for problems. If everything stays green enough for your preferences, you can stay there, or even try a bit lower, but I’d change only about every 2-4 weeks, giving things a chance to stabilize. I think that using all the default settings for a zone initially, but playing with the zone’s cm/hour setting to get the 20 minutes would be the best way to start.
The best thing about Flex Daily is that it responds to ACTUAL temperature, wind and humidity IN YOUR AREA, and to your ACTUAL rainfall from your PWS. So a hot or rainy spell should be well provided for.
Apologies for the dual thread - I’ll stick with this one if I may.
With our own PWS, I absolutely only plan to use Flex Daily. We have seen instances in the past where it could last rain 2 miles away and be sunny in out spot. I found some meter readings from May 2018 and these would appear to more confirm that consumption is maybe nearer to 70,000 to 75,000 litres per week (which will account for numerous directional 90 / 180 deg sprinklers. In addition, no sprinklers operated on Sunday nights and so, my records confirm that each zone was operating for 20 mins 3 times each week. I remember counting 142 sprinklers in total in 2018.
Therefore, this would mean that 142 sprinklers use (70,000 / 3) = 23,333 for once a week watering for 20 mins, so 70,000 for 142 sprinklers for one hour, and therefore 493 litres per nozzle per hour / 8.21 per minute - correct ?
From Google Maps aerial photos, and based on the scale of know measurements on the ground, it would appear that the grounds are aproximately 1050m2 to 1100m2
I’m still trying to find out as to how often the watering is done at this time of year, but maybe this is immaterial now.
My best plan is to possibly setup the fixed schedules for most zones and then just do 2 or 3 with Flex Daily initially and see how they go. I wouldn’t do to destroy the WHOLE place - maybe only just part of it !!!
I was thinking, knowing the aproximate water output, is it possible to somewhat calculate the depth that water for 20 mins would be going down into Clay ? That would be a real confirmation as to potentially how much we are overwatering.
Thanks again, I really do appreciate you input and assistance
Let’s start with this:
Unfortunately, we Americans are deaf with regard to metric measurements. So I’ll do a few conversions:
Let’s take the norm of 1075 m2 x 10.76 = 11,571 square feet. I think there’s an error there somewhere. My single home on a 0.29 acre lot has 9,670 square feet of irrigated area. No way is the beautiful grounds shown in the other thread is only 11,500 square feet. I’ll make a check another way:
Using 75,000 litres per week, that’s 75,000 ÷ 3.785 = 19,815 gallons. Over 1075 m2 or 11,571 square feet, that’s 2.75" of irrigation per week. About double what I’d expect for rain per week, but I would have thought your property was over 23,000 square feet or 2150 m2.
So, I’m a bit confused about the size and flow figures.
That all sounds fine.
The flow of 493 liters per hour average for nozzles is correct. I’m not sure what the 8.21 per minute references.
Well, there SHOULD be a big difference between the water needed per week now (this time of year) versus what is needed in the middle of summer. But I know a lot of people simply going by the 20 minutes per zone rule who never change anything, and wonder why the grass is dry in the summer.
That’s an good idea. However, if you set up any system to average the same water as being applied now (1 hour per zone per week), it should be comparable. But yeah, a couple zones Flex Daily and rest Fixed, equivalent to what you’re doing now (which should not be fixed, as the year’s temperatures vary, btw). Oh, and a Rachio Fixed schedule will vary watering time with time of year, trying to give the right amount of water considering temperatures, but based on historic rather than actual temperatures.
The measurements are pretty accurate I think. Each apartment block is 7m wide, so I have done up a grid. So the pool area is basically 2 blocks x 4 - so about 400m2, the thin section at the top is around 130m2, the main blocked area with the pool and surrounding gardens is about 750m2 (incl pool 400m2), the bottom end of the main gardens is about 320m2, the bottom slip side about 75m2 and the section at the bottom left about 200m2
I meant 8.21 as being 8.21 litres per nozzle per minute.
From recorded details from bills, it would appear that volumes aren’t massively low. Since 7 day timers are in use, I would expect that watering is simply now once a week rather than three times, because the 7 day timer will not allow for once or twice a fortnight. It’s possible that watering could be once a week and maybe the possibility of a reduced duration.
So just to clarify, the schedule I had for watering of each zone for 3 x 20mins per week was for May 2018, but looking at old billing details, it looks like this was possibly increased further during July to October.
As for the Fixed Schedule approach, I believe that the historical data is only available in the USA, so maybe I just need to get it right and work on getting it right, right from the off.
Below is the grid of the whole complex which I used for measuring - each square being 23ft x 23ft - so 529sq.ft There’s a total of about 22 to 23 full squares here
I apologize ahead of time if I’ve got this all screwed up.
For areas clearly visible in Google Maps, I use the DaftLogic Google Maps Area Calculator Tool, located at Google Maps Area Calculator Tool. I came up with VERY different values than you did. Even though I’ve confirmed the measurements from this tool on my own yard, I thought there might be a problem, so did the following simple check: I drew one square using the tool, trying to duplicate one “apartment width” square as you drew above. It looks like this:
Please note that I’ve located and shown your apartment complex in Google Maps, I am not just using the screen shot you posted (although they post the same thing, the Tool uses Google Maps). The tool indicates that one square is approximately 170 square meters or 13 meters on a side, not 7 meters as you’ve stated above. Now, /I/ certainly don’t know your apartments’ dimensions, and you should, but looking at the lower right, the Google scale showing 5 meters seems to agree with the 13 meter square, not a 7 meter one. Is it possible there are 8 apartments across the top, not 4, resulting in an apartment width of 6.5 meters, close to your 7 meters? If so, your calculated area would end up 4 times as high.
I’ve used the tool to calculate the watered area, indicated by your map, less the pool area, and have come up with just over 4,000 square meters, which is almost 4 times your estimated 1050 to 1100 m2.
I’ve mapped the grounds and the pool, and can post those, but there’s no sense in doing that until we can resolve the differences between both our measurements.
Doh, my stupidity, you are spot on. Each “Portal” has two apartments so yes, each length is indeed 14m.
So yes, 4000m² would be correct.
Well, good to know I’m not crazy, especially since Google agreed with me. 
So, this is what I calculated for your complex:
Total area including pool area =5,466 m²:
The pool area, including concrete around it = 1,458 m²:
Subtracting gives approximately 4,007 m².
So your previously quoted 75,000 litres per week would give:
75000 litres / 4007 m² x 10000 cm²/m²… I can’t do metric math, so:
75,000 litres per week = 19,815 gallons per week = 4,577,279 in² per week.
4007 m² = 43,135 sq ft.
4,577,279 / 43,135 / 144 = 0.74" per week.
Trying metric again: 75,000 litres per week = 75,000,000 cm²/wk / 4007 m² / 100² m²/cm² = 1.87 cm = 0.74". Okay, that checks out.
At peak you said you could use 91,000 liters per week —> 0.89" = 2.27 cm per week. Actually, that sounds a little low to me. Typically, lawns need about 1" to 1.5" per week in the summer (I have Centipede grass too), possibly more. So, if I’ve done thing wrong (what are the chances?), I’m not sure you’re going to save water. OTOH, you are very close to the Mediterranean, so that would moderate temperatures and have higher humidity, so it may be right on.
Well, above you mentioned you were getting 200 litres in 2 minutes from most zones. In the 3 x 20 minutes then you’d get 60 x 100 = 6,000 litres per zone, for 14 zones that would be 84,000 litres, so that sounds reasonable too.
That may well be (historical data not available outside the States). Flex Daily is best anyhow IMHO and no harder to fine-tune really. And you have good history of what keeps your grass green.
BTW, you can use the area tool to rough out your zone areas if you’d like. Or I could help you. While 60 minutes per week average might be good, it is very seldom that EVERY zone ends up needing exactly the same thing.
I’m not a big fan of Flex mainly because I don’t quite understand the program. Watering twice a week for at least 30 minutes or more should be plenty for the centipede. You’ll get shallow roots by watering every day so it’s best to give it a good soaking on the day you do water.
Many thanks for all of this. This is interesting - a detail of the WEEKLY litres across a number of years. So the figure I had for May is clearly bourne out from the figures from bills, but clearly the usage was being adjusted every month or two
Of course, the big issue with manual watering is that you were reliant on the gardener to “remember” to change settings. And if he got sidetracked and forgot to change things, or if it was a bit warmer than expected, he could have left things alone rather than reducing the frequency.
So it would appear that when watering was 91,000 litres per week, it must have been a case that some frequencies or durations were increased, especially with watering peaking at 159,000 per week in August 2017 !!!
So back to my Nozzle cm per hour. I know 100% that the 75,000 related to 3 x 20mins, whereas I now know that I have no idea as to what 91,000 (or 159,00 for that matter) relate to time wise. Therefore, it would seem that the setting I need to go with is 1.87cm per hour. However, thinking about it, this is an average and there will be some 90 deg nozzles in the corners of gardens on front of all apartments and along many of the walkways and I therefore presume that I need to cater for the highest user, so maybe I need to go to 2.5 or even higher - what do you think ?
I’m assuming that the whole point of Flex Daily is that it may water once every 10 days this month, maybe only once every 2 weeks in February, maybe weekly in April and so on
I’m assuming @yankeepch that in one sense, using Flex Daily anyway, you could not possibly water daily even if you tried.
BTW, what crop coefficent are you using for centipede grass ? I was thinking 80% or 85%, based on a posting I found online. And what Root Depth setting do you use ? And do you leave it static all year round ?
People don’t really understand Flex Monthly, either, but many use it. ALL the same factors apply to Flex Monthly and Flex Daily, one is no easier or harder to use than the other. The main difference is Flex Monthly uses Historic data, while Flex Daily uses Actual data. Plus Flex Daily considers actual rain received while Flex Monthly does not. One thing I /do/ like about Flex Monthly is that it varies both frequency AND water applied at once from month to month, while Flex Daily varies only frequency. I’d personally like the option of keeping days of watering the same but change time based on a Flex Daily system. Not sure it’s best, but I think it would be a helpful option.
Yeah, that’s what my contractor told me. 20 minutes per zone, 2-3 times a week. And what my irrigation service guy told me. But:
Based on my accurate measurements of both zone flow in GPM and zone area in Square Feet, watering for 1 hour (2 x 30 minutes) gives me in zone 1: 0.44", zone 2: 0.39", zone 3: 0.60, zone 4: 0.80" and zone 5: 1.06". Zone 5 is close to an average required value, the others are woefully inadequate for moderate and warmer weather (here most of the lawn needs about 1.5" per week in summer). Plus, some zones put down almost 3 times more water per hour than others, so the idea of using a constant time per zone is normally not possible.
I’ve found 85% as the correct crop coefficient for Centipede, and while it can vary a lot, a Root Depth of 6" is what I use. If the grass roots are more shallow than that, I want them to grow deeper. And if they’re deeper than that, I don’t want to apply any more water at once than I am with 6". And yeah, I leave them at that all year round, because I’ve not found any season or month-specific values for Centipede. I do think Rachio’s defaults for warm season grass are not even close when using Centipede, but probably are fine with Bermuda or St. Augustine.
Also, in most of the U.S. South, people don’t water their grass, especially Centipede, after about November 1, as it goes tan and dormant. And while it’s true, it doesn’t need much water then, and here in SC we usually get a lot of winter rain, the roots are still alive and a long dry spell will definitely cause problems. So I cut back on my water required (Crop Coefficient) and water at once (Allowed Depletion) to close to half the regular values for this winter, so if things really dry out, it will water and help, but won’t water much. So far, leaving Flex Daily running, it hasn’t needed to water at all since Nov 1.
Flex Daily will certainly work perfectly for me, given your explanation of it’s pattern of keeping the amount of watering constant, but altering the frequency. I created several test zones and found three variations of 22, 21 and 19 mins. All of these had 6" depth of roots, so the variation was caused by various settings of the Crop Coefficient, the Efficency and the Nozzle Sizes. I’ll look again at the frequency these have created and look to implement that.
It’s somewhat difficult for me being in Ireland and the whole setup being on Spain, and due to Covid, it could be several months before I get over there to look at things myself. But I hope to possibly post the controller over to Spain for installation by the guys there.
Another three questions please -
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I have a zone setup which has calculated watering time as 22 mins. No matter what, will this always be 22mins and simply alter the days between watering ?
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Whether a zone has 4 or 40 sprinklers, I’m thinking that the nozzle size should be based on the LARGEST required on the basis that if it was based on the average, it wouldn’d water some areas enough
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If I setup a zone, is it basically the configured area size which ultimately determines the quantity of water. I mean, i can have a zone of 4 nozzles and a zone of 40 nozzles, but yet you cannot configure the number of nozzles in a particular zone anywhere.
Yes. Flex Daily calculates how much water it takes to “fill up” your soil to the Allowed Depletion and always waters that amount. Deep watering helps promote deep root growth and helps the grass get through dry periods. During really hot summer, it might water every other day, then much less often in cooler weather.
Forget about how many sprinklers you have in a zone. While Rachio does call it “Nozzle Inches per Hour”, it is really the total average inches per hour applied by all your nozzles in a zone to the area within the zone. That’s why I recommend measuring (manually or using the Google map area calculator) the AREA of each zone, then by running the zone’s irrigation for some minutes, measure the actual water used. From that, you can calculate the average “Nozzle Inches per Hour” that you need to input. Oh, I guess yours will be “Nozzle cm per Hour”.
Is explained above, individual nozzles mean nothing here. Only the total water applied to the zone. While Rachio’s averages for each sprinkler type may be reasonable, I’ve not found them to work for me, and have decided the area vs flow method to be best.
I’m sure I must be doing your head in !!!
So just thinking further - I have 4000m2 and 14 zones, so for now, I should really make each zone then 285m2 (which seems absolutely a huge area for 9 to 12 sprinklers) - correct ?
And I think I’ve found the perfect settings for 20mins - 15cm root depth, 80% efficency, 85% crop coefficient and 3.75cm nozzle size. I’ve left the Available Water at 0.15mm/mm - which is the system generated value.
I’ve played with various settings on the nozzle sizes and found that if I set the nozzle size for 3.5cm, it creates a schedule for 21mins, and if I set it to 4.0com, it creates a schedule for 19 mins. If I set the nozzle size for 5cm, it creates a schedule for 15 mins.
If I was to set the nozzle size to 1.87cm, the schedule runs for 41m