Starting small with any new tech or platform is always my suggestion, so can understand and agree with taking small steps.
Also, I think lawns will typically "tell you" well before they are in real trouble, they are often particularly resilient as long as you keep an eye on them, and will display signs of distress early enough to respond.
You know...if one had the "perfect soil moisture sensor" package (Ag & Research ones come a lot higher price range than what we are seeing in these Ecowitt modules) set in the "most representative soil location" then MAYBE they would drive the irrigation optimization the way folk hope...but other than a confined soil package like a pot or a small bed...it is hard to accurately represent the whole of a large lawn (with varying tree canopy), garden, or field. Sensor accuracy aside...everything just doesn't take up/use/retain water the same.
I have come to believe experience learning the vegetation and soil water requirements (given a particular vegetation, soil, time of year, sun, temperature, humidity, and rain) is more beneficial than dependence on these moisture sensors.
That experience results in setting a few "in-the-ballpark" watering schedules appropriate for Spring, Summer, and Fall.
The one thing I WOULD like to accurately measure is rainfall (and approximate persistence in the soil based on subsequent drying)...that is the one thing that would most impact if the watering schedule should be paused/skipped for a couple days or not.
I started that project with a hacked ZigBee contact sensor wired to this sensor package
https://www.allelectronics.com/item/rws-1/rain-sensor/moisture-monitor-w/relay/1.html
and I got waylaid on figuring out how to box/tray, angle, and expose the sensor plate to retain some water (i.e. sponge), and drain excess. Turns out that's the more complicated part to get right 
I've been using the Rachio interfaced with the Weatherflow Tempest and it's been doing a nice job. The Rachio allows you to configure the soil type, plant type, grass type, shaded or unshaded and level or sloped terrain for each zone. That along with the data from the Tempest, rainfall current, past and forecast, wind speed, temp and humidity gives me a pretty good schedule. Having been in the Lawn & Ornamental pest control business for 30 years I do watch for proper irrigation very close.
wittboy
Now on Amz:
https://www.amazon.com/dp/B09QKXMKS4
And a reviewer says they've connected it to HE
https://www.amazon.com/gp/customer-reviews/R19G80MFPPTKWI?ASIN=B09QKXMKS4
To clarify, does the Wittboy uses the existing Ecowitt-HE app or require @kahn-hubitat 's custom device drivers?
It should work fine with any of the Ecowitt drivers (including my Ambient/Ecowitt driver)... because it says it can go to custom sites using the "Ecowitt protocol".
No it needs my custom driver for now as i believe changes have not been integrated yet. It has nothing to do with the app config. That comment is misleading.
Download the Hubitat app
