Hello,
There are actually solutions for this, although not from OpenSprinkler.
For example, together with the “Xiaomi flower care” humidity sensor, there is the “Flower Care” app, which can do much more than just flowers.
When I search for “tomato” I get:

The sensors monitor the plant. This is what my arched hemp looks like, for example:

And now comes the good thing: together with a Raspberry and OpenSprinkler, you can control the irrigation!
https://OpenSprinklerShop.de/forums/topic/tipp-xiaomi-mi-flora-plant-sensor-einbinden/