# The theory of 1" of water per week



## creediddy2021 (Mar 27, 2021)

After nearly 4" of rainfall within the last 72 hours I've come to conclusion that more water for our lawns results in greener grass. The argument/disagreement of overwatering by using more than 1" of water per week is simply more precaution. If Mother Nature provides nearly 4" of water on my lawn within 72 hours without showing signs of overwatering, then why is theory of watering more than 1" just a precaution? My lawn is able to absorb this without any issues. I keep my HOC around 4".

Again 1" is a baseline and depending on temp and climate you would need to adjust to more than 1" per week. However is even 2" of water enough to keep your lawn green with weather conditions above 85 degrees?

Just opening this up for discussion…


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## Delmarva Keith (May 12, 2018)

I think it's an inch of irrigation (as opposed to total water) with the assumption that there will be some rain. The inch is just a starting point that seems to work out ok most places. Around here in full sun, an inch with no rain isn't enough to prevent turf from going dormant. About an inch and a half is closer to the mark. OTOH, in partial sun areas, an inch is too much and will tend towards soggy or close to soggy.

If you can get 4" of rain in one shot without any soggy spots or runoff everywhere, you must have good drainage so count yourself lucky. Around here it's a balancing act of enough to keep things growing but not too much so the soil is not already saturated when a big popup thunderstorm hits.


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## creediddy2021 (Mar 27, 2021)

Great points Del! That is my point I'm making…we are making "assumptions" that 1" is adequate and "overwatering" could occur. In reality with weekly rainfall and irrigation it's closer to 2-2.5" needed to keep yards green. Temps in 90's and over 90's need at least 3" of water or more weekly. Just an observation…


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## corneliani (Apr 2, 2019)

Here's where you can nerd out on that stuff. I learned more through reading that thread than any online resource I've come across. Awesome job by gman on that.
https://thelawnforum.com/viewtopic.php?f=5&t=19653


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## Ware (Jan 28, 2017)

@creediddy2021 curious where are you hearing that more than 1" of rainfall or irrigation a week is considered overwatering?

I've often seen it used in the context of a recommended minimum under average conditions, but I can't say I've ever heard of 1" recommended as a maximum amount.

:dunno:


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## Green (Dec 24, 2017)

I've heard 1 inch of water. I've heard 1 inch of supplemental irrigation. I followed the inch per week thing. I don't do it anymore. It's not a rule. It doesn't necessarily "work"...it's just an approximation for an average lawn in average conditions in a certain part of the world, but the math doesn't verify it. More like broken clocks being roughly correct for a portion of the day, I've come to the conclusion it's just an average meant for uninitiated, busy, or lazy people.

I almost started a thread on this exact topic myself recently, but then I decided not to, because I didn't want to confuse anyone.


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## Oyster Shark (Aug 24, 2020)

Thus far for the month of June I have irrigated 9.8 inches.


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## Green (Dec 24, 2017)

Oyster Shark said:


> Thus far for the month of June I have irrigated 9.8 inches.


Yikes!!!!!!


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## Oyster Shark (Aug 24, 2020)

Crazy right? Around a 1/3 of an inch per day for the entire month of June. Percolation tests show it takes many hours for complete penetration of 1'' of water. Lawn never goes to bed "wet." Sprinklers run 1AM to about 7AM.

So I turn the sprinklers on and forget about them...

I'm going to start a humic acid program with fertigation. Hope to change some stuff.


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## corneliani (Apr 2, 2019)

Ouch! I've watered a total of 1.5" this month (45min sessions out of MP Rotators for approx 1/2" water each time), and this is on a cool season turf in the south!. I'm really trying not to water until I see some stress, hence me fighting the Rachio algo's to skip watering all the time. 

Last month I let the system do its thing more as I'm trying to learn it & still only put down 3" for the month. I think I agree with @Green in that there are too many variables to account for to make it a hard rule that the turf needs 1 - 1.5" of weekly irrigation. Learn to read your turf and wait until it asks for it.


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## Oyster Shark (Aug 24, 2020)

Yes. You need to read your turf. Walk it with a probe and pull core samples.


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## creediddy2021 (Mar 27, 2021)

@Ware…I read several articles online and this forum included and many people recommend about 1" of water per week. I hear nothing about additional irrigation along with weekly rainfall.

This is why this is great conversation as many people don't follow the 1" per week as many people water more than 1" per week. I look at it as a minimum. Also the idea of overwatering with hot climate conditions seems like anyone would be underwatering their lawn on a weekly basis.


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## Ware (Jan 28, 2017)

creediddy2021 said:


> @Ware…I read several articles online and this forum included and many people recommend about 1" of water per week. I hear nothing about additional irrigation along with weekly rainfall…


Again, I've been around a while and I can't say I've ever seen anyone claim that more than 1 inch of rainfall or irrigation is "overwatering", as you suggested in the OP…



creediddy2021 said:


> …The argument/disagreement of overwatering by using more than 1" of water per week…


Hell, I'd love to get a few inches of rain this week. :lol:


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## creediddy2021 (Mar 27, 2021)

@Ware...right now we are sitting at 3.71" of water in the soil in my area. Over the next 2 days we are looking to get another 1.5" of rainfall. I will definately need to be putting down the diseaseEx as I believe there will be minimum sunlight as well to dry this all out.


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## Delmarva Keith (May 12, 2018)

To add another dimension, with the discussion on amount, what is everyone doing for frequency? I think it's interrelated. When I bought my house here years ago it came with irrigation system set to every day. Not good. Fostered lots crabgrass and other shallow germinating weeds like crazy. Plenty of sedge too.

I water turf 2x / wk. I'd like to water 1x / wk but that much water at once tends to make things soggy for a day or two.

So along with how much, how often?


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## g-man (Jun 15, 2017)

@creediddy2021 Someone already referenced the ET Irrigation guide for you to read. I think you should read it.

This is part of the first paragraphs:



> _tl;dr_
> 
> 1in water/week is not even close to accurate. Try to water your lawn to apply between 0.4-0.6in of water when it shows signs of wilting. This could be every 2-3days in the dog days of summer.​


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## g-man (Jun 15, 2017)

Delmarva Keith said:


> To add another dimension, with the discussion on amount, what is everyone doing for frequency? I think it's interrelated. When I bought my house here years ago it came with irrigation system set to every day. Not good. Fostered lots crabgrass and other shallow germinating weeds like crazy. Plenty of sedge too.
> 
> I water turf 2x / wk. I'd like to water 1x / wk but that much water at once tends to make things soggy for a day or two.
> 
> So along with how much, how often?


It depends on spring/fall vs summer and your soil type. In most cases, every 3-4days works the best during summer. Once a week in summer/fall (assuming no rain).


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## creediddy2021 (Mar 27, 2021)

g-man said:


> @creediddy2021 Someone already referenced the ET Irrigation guide for you to read. I think you should read it.
> 
> This is part of the first paragraphs:
> 
> ...


Thanks g-man! Yes it was a great read! Thanks for sharing…


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