What is right root depth for St Augustine grass?

4-6 inches. Depends on a lot of variables.

I don’t have experience with this type of turf so maybe someone else will chime in, but if you shoot for 6 inch on a flex, I’m sure you can get it there. Lots of posts with annecdotals all over the place.

It is around 4 yrs old. Our home is in Austin, TX.

I’m not selling this, but I have one, and is the greatest lawn tool I own. http://www.houzz.com/photos/10234877/5-in-1-Planting-Tool-contemporary-gardening-hand-tools

See how deep your roots are, and can go.

@plainsane thank you for your help!

@Videoguy the root depth for this type of grass is about 4"-6". Setting up your schedule with that type of root depth will ensure your yard is healthy. Start with a root depth of 5". If you notice your grass discoloring then move up another inch.

And to clarify because I just made this mistake (I r the dumb sometimes) move to 4 inches.

Not trying to be pedantic @George, sorry

@plainsane @george I was wondering which was up. :wink: Newb question but why might a root depth setting of deeper than normal result in grass discoloring ?

@plainsane no worries! You are a tremendous asset to the community. Please keep up the good work!


If the setting is too deep then the soil could become over-saturated, which could cause the roots to drown.

@george That makes sense. I have my RZD set to 7" for bermuda and have been wondering if that’s too much. Previous to my recent switch to Flex our AZ landscaper used three 12m waterings per day for 3 days of the week. At a 7" RZD I’m at about every other day and 20 mins (two 10min cycles).

Would the discoloration be any different if I’m under watering ? Any guidance would be appreciated. Otherwise I’ll just monitor and tweak if required.

also, if running on a flex schedule, it could cause a much longer delay in watering cycles so the grass could also become drought stressed.

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Great point!


The coloration can be a bit tricky because when the grass is distressed from over or under watering it will appear grayish-blue.

Here is a great 2 part test to tell if your lawn is over-saturated:

1.) If the grass appears grayish-blue, 2.) step on it, if the leaves do not bounce back up that’s a good indicator that the yard is over-watered.

@George. Got it. Thanks!

No problem. Just glad I could help.

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I just enabled Flex Scheduling via the web. New
Rachio Gen 2 owner with 2 year old Bermuda warm season grass (from sod)
on mostly flat terrain.

Default zone setup was root depth of 9 inches. Adjusted to 6 inches
based on 4-6" recommendation. Should I start instead with 5"? Has been
a rainy spring season so far.

@Miles267 The 4-6" recommendation above was for St. Augustine. I’m not sure where you live, but here in Phoenix the recommendation for bermuda is 8-10". There are a variety of factors that would come into play such as the soil type, etc., as to how deep your roots will be able to grow. The link here has some information, including a link to a Phoenix based watering guide for Bermuda.

Thanks. I’ve checked for my geography (NW Arkansas). Pg. 3 suggest 4-6" depth here. I’ve set to 6" now.


@Miles267 Great article. It’s nice to be able to find publications from your locality that spell out those kinds of details. Thanks for sharing it.

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Thanks for sharing that article! It really helps the forum!

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Newbie on the Rachio block. I set the depth to 5’’ and good to read its what is recommended…am in North Houston, Spring area and have st. Augustine warm grass. Wondering if i should lower the AD to help grow roots deeper ? Thanks