Created New Flex schedule with measured inputs; expected a different outcome


Hey Everyone. I’m still getting adjusted to the lingo for irrigation, but I’m trying to get there and want to be good at this eventually. I live in Houston where the summer months are ridiculously hot while also having some of the worst soil ever created. Establishing a good root system is already a uphill climb. I purchased a soil probe to determine root depth and have a look at the makeup of this soil. After checking a survey of my area the entire neighborhood is listed as “Urban Land” with no measured data available. The soil has some clay and what I believe to be sand. We have treated the ground countless times with Gypsum in order to break up that clay. I determined that my St Augustine roots were only reaching MAYBE 3 inches. Thats being generous. All the reading I’ve done has indicated that with the roots being so shallow and not penetrating deeper, I should be watering deeper less frequently to promote deeper roots. After doing the catch cup tests and adjusting the inputs for efficiency and root depth, I figured that would be the outcome. Instead my water time for each station went WAY down and set to water 6 days in a row. Not to mention that the soaking that used to take place before my adjustments is now gone. The ground is very hard here in my area. The clay is obvious in the soil by how hard the top layer is. Water tends to soak in slowly. I figured my settings would lead to that too.

This doesn’t make sense to me. The idea that the grass won’t burrow deeper for water if there is always water available at the surface does make sense to me. I think I would need a less frequent, longer watering.

Am I looking at this wrong?


I’m in a similar boat as you; there is a learning curve. The simple answer is that the Rachio watering optimally for the conditions you have (frequent shallow watering for shallow roots), not the conditions you want (deeper watering for a deeper, resilient root system). The two “knobs” you can work with are crop coefficent and root depth. First reduce crop coefficient by 5-10% and observe. If the grass is still too happy between waterings increase the root depth by 1" increments then back off when it looks like you may be going too long. FYI it took me about two years and a dedicated fertilizer regimen on a KBG lawn to see a marked improvement; I don’t know how quickly warm-season grasses adapt.

I would recommend doing a mason jar test per This article. I did it last week and my actual soil is radically different from what the USGS says. It’s not surprising since I live near a gravel pit, but also not what I would expect from fill dirt in my area.


Nice work in coming up to speed and paying attention to the details early on.

I would recommend finding a way to get your soil available water content identified. That’s a huge factor that if you don’t get close, you’ll end up struggling to get the other settings dialed in. Some areas have free soil testing through govt. agencies or universities. Otherwise, if you don’t mind spending whatever the cost would be for you look up soil testing agencies in Houston to see what they might charge. If not, there is the mason jar test that @ThisIsntFunnyAnymore. I personally struggled a bit to make sense of my mason jar test but I know that others have had reasonable results.


@ThisIsntFunnyAnymore and @azdavidr thank you both for the replies and advice. I completely understand what you said about Rachio watering for the current situation instead of watering for the wanted result. I made a change to my soil type for the time being to get the deeper waterings st about 2 days a week. I plan to do the Mason jar test as suggested and send a sample to A&M for pretty cheap. Hopefully after that I can get comfy with a daily flex schedule