Thank you all for your kind and informed replies. You've put me on the right track!

The continuous loop code finally works great in my updated RPi-based plant watering system but errors out when the maximum recursion depth is exceeded. The logic requires taking different paths through the code, depending on tests along the way. Not having GOTOs in Python, I used functions to perfor...

Yes, PhatFil. Moisture sensing is evidently something of a black art. In V1, I did apply some water, then delay for absorption time, read again, then apply more water if needed, etc. But the conductive sensors were worthless, especially with the way-too-long cable runs I was trying to use. I'll give...

Thanks, jbudd. Your idea is to have the moisture sensors connected wirelessly to the Pi. Cool. Maybe in V3. But for V2, since my garden isn't big enough to require wireless connectivity between the Pi and the plants, I think I'll just run one 2-pair speaker wire from a RS-486/USB adapter, connected ...

I'm starting V2 of my plant watering system. V1 worked ok, but I used inappropriate moisture sensors for the distance I needed covered. It ran on an Arduino. Since I have to re-do the entire input side of the process for new sensors, it's an opportunity to upgrade to Raspberry Pi and add Internet co...