# time of day for irrigation



## MDJoe (Sep 16, 2019)

Most places recommend irrigating around dawn-ish or slightly before for obvious reasons. However, if you are in a situation where the size of your lawn and limited capacity of your water system (well yield, in my case) makes it impossible to water the entire lawn during that timeframe, what's the second-best?

Would it be better to either go a bit earlier (3am), or water a bit later into the morning, but stopping before evaporation really gets rolling (say, be done by 10am?)


----------



## SpiveyJr (Jun 7, 2018)

How many zones do you have and how long do you run each zone to put down 1" of water? Why not schedule different zones to run on different days?


----------



## Harts (May 14, 2018)

^ +1 This was going to be my suggestion. There is nothing in the rule book that says your whole lawn HAS to be watered on the same day.


----------



## MDJoe (Sep 16, 2019)

14 zones at about 2 hours each from what I figured out.


----------



## MDJoe (Sep 16, 2019)

I'm still trying to figure out if I can even do it.


----------



## gregfromohio (Aug 14, 2019)

I didn't think that TTTF needed all that much water.....


----------



## MDJoe (Sep 16, 2019)

Well yield is about 7 GPM max, so figure on a max usable of around 6 GPM to design the irrigation system. 
I'm looking to irrigate about 1/3 of an acre. It takes 27,000 gallons of water to put 1" on an acre, so for 1/3 of an acre, that's 9000 gallons. So regardless how the zones are put together, that's:
9000/6 GPM = 1500 minutes of watering per week to get 1" per week. That's 25 hours.

Either I go with more zones at a higher flow rate per sprinkler head, or fewer zones at a lower rate, it still takes 25 total hours to put out that much water. So figure if I run it every day for part of the yard, it'll have to run 3.5 hours per day to get there (assuming no rain falls that week)…and that's only a third of my lawn (basically the front and sides).


----------



## j4c11 (Apr 30, 2017)

Just for clarification, 1 inch per week is for when temps hit the 90s. Once this heat wave breaks you shouldn't need to water until about late April.


----------



## MDJoe (Sep 16, 2019)

I know, I'm only planning.

Although, for what it's worth, the heat wave is going to break, but there still no rain to speak of in the forecast. It's dry as a bone.


----------



## RozWeston (May 20, 2018)

I water about 7000sf in five zones, 17 sprinkler heads. I'm also on a well.

My well is deep, and has great water - but it's old. So I worry.

After my overseed I was running all five zones, three times a day, for 15 minutes each zone. As the grass started to establish I was really able to tell where water was needed the most, and where I could cut back. Was very noticeable - the germination, height, color and how the ground felt to walk on it told me everything I needed.

After about three weeks I was able to reconfigure my days/run times. Shade, slope, differences in soil etc all factored in to the success of the watering. We have a pool and the stone coping around it gets very hot and grass has a hard time staying moist around that area - so those zones get extra. We have a TALL cedar hedge down one side of the property with tons of shade, the other half of the yard is in full, blazing sun all morning and all afternoon.

After three weeks I was able to rebuild the schedule based on what was totally obvious. One of my zones I run once a week. Two of my zones I run three times a week. The other two twice a week.

I alternate days, and pair up the zones that need the least water on the days when I'm running heavy on the other two.

Now when I walk on the lawn, everything looks and feels uniform.

But no, I don't run all zones every day. I thought I needed to. But you I don't.

Also, cheers to no water bill!


----------



## SpiveyJr (Jun 7, 2018)

You might want to invest in a smart controller. Worst case scenario is you have to water 25 hours a week, no? You will be surprised how little or less of this number you will actually be watering when your lawn is at field capacity.


----------



## MDJoe (Sep 16, 2019)

Most of the time I won't have to water that much, maybe one week out of every three in the summer. The problem is, this year I would've been watering that much from mid August until now. We've had virtually zero rain since then. So I have to at least have the capacity to do so, otherwise why bother?

Last year, there were only about three or four times I would have had to water...a few weeks in late June/early July, and maybe two other times. Unfortunately the 65" of rain we got last year wasn't quite perfectly distributed, we still had spells where the soil was dry 6" down in between rainy periods.


----------



## MDJoe (Sep 16, 2019)

RozWeston said:


> I water about 7000sf in five zones, 17 sprinkler heads. I'm also on a well.
> 
> My well is deep, and has great water - but it's old. So I worry.
> 
> ...


I would never expect to have to water daily, except when seeding.


----------



## Guest (Oct 2, 2019)

How much to water the lawn has a lot of factors which would include:

How much you want to spend?
How often you mowing and how often do you want to mow? What height do you cut?
Do you want to keep it green through a hot and dry summer, or are you ok letting it go dormant and coming back in the fall? Even 1" a week may not be enough for cool-season grass, during a hot July on a full sun lawn. Sure 1" a week will keep the crown alive but it will go brown. 
How much sun and shade does the lawn get?
How is the soil and has it been well treated over the years?
How is your sprinkler coverage and how long do you have to run it to put down a half inch of water?
What is your grass type?

Probably 50 other things you could consider but you get the idea.


----------



## g-man (Jun 15, 2017)

Most soils cannot handle 1in of water at once. I use 0.5in every 2-3 days during the peak of summer. Each zone is tracked and irrigated based on sun/shade areas.


----------



## MDJoe (Sep 16, 2019)

g-man said:


> Most soils cannot handle 1in of water at once. I use 0.5in every 2-3 days during the peak of summer. Each zone is tracked and irrigated based on sun/shade areas.


True, but I have tested mine...a foot-deep hole filled with water drains in about two hours.


----------



## g-man (Jun 15, 2017)

I don't understand how percolation at 12in matters. Can you explain?


----------



## MDJoe (Sep 16, 2019)

If my soil can absorb a foot of water in two hours, why not an inch in a couple hours once a week, or even twice? Just a question.


----------



## MDJoe (Sep 16, 2019)

A lot of the conventional wisdom says you're better off watering an inch all at one time once a week versus half an inch every couple days. That may be different for lawns, but considering that, is there a difference between TTTF and KBG in that regard?


----------



## g-man (Jun 15, 2017)

1) crop coefficients for TTTF, PRG and KBG are normally reported at the same value (average of 0.80 from ET0). This means that on average, they all use about the same quantity of water.

The conventional wisdom of 1in a week is just wrong. In the summer it peaks around 1.5in per week.

This article has a ton of good info to get your started in water capacity practices.

This is from rachio pages: https://support.rachio.com/hc/en-us/articles/115010542588-What-type-of-soil-do-I-have-

Rachio had a good explanation of the whole process, but I can't find it.

How to calculate ET0


----------



## 1028mountain (Oct 1, 2019)

How do measure an inch of water? I read somewhere a tuna can? For whatever reason I can't imagine how long I would have to run my sprinklers to accumulate that much water across my entire yard.

FWIW I am in MD as well.


----------



## MDJoe (Sep 16, 2019)

g-man said:


> 1) crop coefficients for TTTF, PRG and KBG are normally reported at the same value (average of 0.80 from ET0). This means that on average, they all use about the same quantity of water.
> 
> The conventional wisdom of 1in a week is just wrong. In the summer it peaks around 1.5in per week.
> 
> ...


Good stuff. Thanks!


----------



## g-man (Jun 15, 2017)

@1028mountain

Any straight wall container in the irrigation zone. Set the system to run for 30min and go and measure the inch of water in the cup. You can then figure out how long to run the system to get 1in. Multiple catch containers in the area are good to get a good representation.


----------



## badtlc (Aug 22, 2019)

MDJoe said:


> A lot of the conventional wisdom says you're better off watering an inch all at one time once a week versus half an inch every couple days. That may be different for lawns, but considering that, is there a difference between TTTF and KBG in that regard?


That just isn't realistic for many people. You have to have perfect soil to be able to do that. As the other poster said, for most of us, 1" of water using irrigation results in significant amounts of runoff that doesn't get absorbed.

I found that during the 95F+ heat, my grass requires water about every 3 days no matter how much water goes down. Because of this, I just set the routines to run every three days at a minimum amount of time. As it gets hotter and grass needs more, I turn up the season adjust % and up the runtimes required to keep the grass green.


----------



## Guest (Oct 3, 2019)

My findings have been the same as badtics. (we also are in MO not MD)

I am not sure what soil is like in Maryland. If your soil absorbs water that fast, it would seem that it would have more sand?

Even during a summer drought, if I run a zone for 20 minutes at once I will get a little bit of runoff. One of my favorite features of the Rachio controller is how it would break down a 20 minute watering per zone down into 5-minute segments and cycle through the yard 4 times. Opposed to watering each zone for 20 minutes straight and having some runoff and not all the water gets absorbed. I think the split watering cycles are one thing that did help my lawn and really helped it soak up the water.

Even for those with sandy soil, during the summer heat where I live the lawn responds way better to a half an inch of water 2-3 times a week than 1" once a week.


----------



## MDJoe (Sep 16, 2019)

Does it help to use a sprinkler head with a lower IPH rating?


----------



## MDJoe (Sep 16, 2019)

macdawg said:


> My findings have been the same as badtics. (we also are in MO not MD)
> 
> I am not sure what soil is like in Maryland. If your soil absorbs water that fast, it would seem that it would have more sand?
> 
> ...


Many people in MD have clay, but my yard is a sandy loam in most areas. A bit more of a silty loam on the south end, though.


----------



## MDJoe (Sep 16, 2019)

I guess my point was, as long as your predawn irrigation starts late enough that dew is already likely to be on the grass, does it matter much at that point? Water is water.


----------

