Looks like Gardena are releasing a new smart sensor smart Sensor | GARDENA
Pretty spendy but if it is more reliable than their timers and can integrate it via a hub it’s less than ideal but will put up with it if the information it sends is accurate
I have an old gardena moisture sensor https://www.amazon.se/-/en/Gardena-Floor-moisture-sensor-irrigation/dp/B000NUVMSG?th=1 which I wouldn’t mind trying to esp it, it’s fairly chunky so more suited to larger beds.
With the help of this post I’ve compiled the esphome yaml. I’ve yet to wire it up and see what I blow up 
