Lawn watering advice

Hi all,

My apologies if this topic has been covered before.

I have a 2nd generation Rachio. I’m in Southern California and my front lawn gets a lot of sun. I reseeded it in the early spring and it looked great for a few months but the high heat of the mid-to-late summer (90-100 degrees) has killed much of it.

I have my Rachio set to Flex Daily 6 days a week after 6am with a total time of 16 minutes per watering and the smart cycle on. I’ve noticed that it waters less frequently than I would expect considering the heat (my soil moisture as I write this is 13% and there are 4 days between waterings - although it is a touch cooler this week) and doesn’t split up waterings to allow for soaking. Are there settings I need to adjust to avoid a very brown lawn next summer?

Thank you!

First off, are you sure that you have your nozzle PR set correctly? If you used the default settings, they might be quite a ways off…

To bump the frequency, you can adjust the crop coefficient up 5-10%, or since this is newer grass, adjust the root depth to 4-5" vs the default 9". As the grass matures, you can lower that back down an 1" at a time.

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Yes, I believe all the normal settings - including nozzle pr - are correct. It’s the advanced settings that lose me, so I appreciate the tips on crop coefficiency and root depth. I’ve made those adjustments. Hopefully they’ll do the trick.

Do you know why make and model of sprinklers you have?

I they’re Rainbird 1800 series sprinklers with Rainbird high efficiency adjustable nozzles.

So just to confirm, you have the “inches per hour” of your nozzle set somewhere around 2"?

I had it at 1.5 but just adjusted it to 2. Thank you.

Well, it doesn’t necessarily have to be 2", but Variable Arc Nozzles are known for being, well varied in their precipitation rate. They can have HUGE swings in PR’s with changes in pressure.

I only said 2" because it’s somewhat the average for me not knowing which series you have (8’, 10’, 12’ radius).

If I recall correctly we have a mix of series - 8, 10 and 12 - depending on the areas they’re targeting. It sounds like 2" is a good setting to use. It also sounds like next time we shouldn’t choose variable arc nozzles.

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They are really convenient with their infinite adjustability, just not usually the most efficient at putting down water when compared to a fixed spray nozzle.

If you need thr adjustability, I am a BIG fan of the Hubter MP Rotator nozzles. Allow for the same infinate adjustability, but the PR’s are almost identical in every arc or radius!

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Thank you for the tip. I’ll keep an eye out for those when we’re ready to replace the existing nozzles.

Thanks again for all the advice too. It’s sad to see a nice lush lawn go brown the way ours has. Hopefully these changes will keep it from happening again next summer.

I am assuming that you have a cool season lawn type? If so, your lawn isn’t dead, it most likely went into dormancy, once the temps drop to the mid 70s, you should be able to give your grass a good deep watering and some fertilizer to bring it back out of dormancy. Fall is a good time to seed again if you have bare spots.

As far as next summer, in order to keep a cool season lawn from going into dormancy, you will need to keep the grass as cool as possible. You can set Rachio up with a manual watering for your front lawn and have it water the 16 minutes but as an example, water for 2 minutes with a 2 hour soak. This would start at 6am and end at 8pm each day in the summer only. If you water for 16 minutes at 6am in the morning, your grass is just baking all day in the direct sun without any relief. Using the information that the other poster is providing and getting your setup correct and maybe also doing a “Tuna can test” on your lawn to make sure that you have setup your system with the correct rate should ensure that your grass is getting the correct amount of water. Then adjust your watering time based on that test.
Also, check out Lawncology and/or Lawn Care Nut on YouTube, they have a couple of videos on how to check your irrigation system for correct watering as well as how to deal with issues you’ve ask about in your original post.

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Thank you. I’ll check out Lawncology and Lawn Care Nut. I appreciate the tip.

If I remember correctly we put down Bermudagrass as it came highly recommended at our local nursery.

I could be wrong but it seems dead based on appearance and the weeds that are starting to grow in its place. I’d love to be wrong but I’m not hopeful.

Bermuda grass is a warm season grass and should be ok in the heat you’re experiencing…have you checked the setting for that zone to make sure it’s set to warm season grass?

Here is the irrigation tip out of the Lawn Care Nut warm season grass guide:
“Bermuda is a middle of the road water drinker. 1 inch of water a week is going to be fine for most areas outside of the very heat of summer. In July and August if you are not getting rain help where you live, your Bermuda will likely need 1.5” per week. Just be sure to keep each irrigation cycle at ½” of water and separate your waterings by 2 - 3 days or so.”

Unfortunately you will have to wait until late spring to reseed your Bermuda lawn. Until then I would suggest getting a soil sample test so you can get an idea what issues you may have with your soil. Also, take one of your longest screwdrivers and see how far you can push it by hand into the ground, if you can’t push it more than a couple inches you may have a really compacted soil. If it compacted, your grass is going to have a really hard time growing the deep roots that it needs to survive a hot summer. Compacted soil can be helped with either core aeration or there are liquid methods that you can spray from a hose end sprayer. If you get some of these things started now, by the time you reseed in late spring, your soil will be better prepared and you should get a much better result!


Keep in mind that changing the pr from 1.5 to 2 decreases the amount of water applied. Hence even more brown grass. Changing the root depth doesn’t apply more or less total water. It just changes how often and how long.

Do you overseed with a winter lawn where you are? It might be a bit late in the season to do much with the Bermuda. Once nighttime temps drop into the 50’s bermuda starts to struggle. Depending where in southern California you are, Bermuda might be a year round grow, IDK.

Either way, you probably didn’t kill the Bermuda, it may have just gone dormant. A good fertilizer and more frequent watering from the changes you made will probably bring it back.

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A better performing Variable Arc and Radius nozzle is Toro’s PRN
Even going with Toro PCN with set Arc settings are far superior performers to a RB HE Vari Arc

. … and please don’t use their 15’ half as there are two large gaps @ 13’ left and right @ 45 degrees on each side. We found this out as we are Beta testing for the new sprinker requirements just passed in California for 2020 August 14, 2019

“Resolution 19-0814-7 that mandates that all spray sprinklers must include a pressure-regulating device effective Oct. 1, 2020.”

I install all sprinkler heads with IFR technology you can PM and I can provide you the information. Best thing ever! Better than a Pressure Regulating manufactured Head then along with the Rachio controller :grin: just stellar!

I can dial them down to 7" radius with IFR!

I have not tried the MP800, their PR is double and better than the original MP1000. I guess I should throw them on a stand since I have a couple kicking around in my box.

I do use the larger MP2000 and 3000 where Hydraulics in the system won’t allow the PRN gears to be driven with lack of flow.

Glad someone touched base on the turf requirements, and characteristics @XCrosswordsX Which is correct in regards to heat and the UV in So Cal.

The Crop Coefficent is 5% higher and its realistic that you need to cool down the first 4" of soil for the turf not to suffer.

You mentioned the fact that you seeded and another problem you may have encountered is that it was cut way too short to soon for the grass to mature enough . It happened to me with the gardeners, as my re-seeding on a clients property was in sporadic places and I didn’t not tape off or isolate the areas. Thus before the nodules to split to grass to mature and photosynthesis process to occur, they killed it.

Also, there is a seeding schedule, I found I believe it is in “Fixed” schedules to use…that should be helpful, I did not know that.

Your in So Cal I can direct you to sites we have retrofitted with IFR and parts to retrofit are available locally, and I am happy to demo for you.

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