I finally got my watering to work consistently. All it took was replacing the MOSFET with a switch relay and some persistence in getting the damn ESP8266 to connect to the network for more than 5 minutes. I also had my first crop: green beans (or as they seem to be called in the US, string beans). Still waiting on the tomatoes, but I fear the aphids may have undone the good work so far. So, here's the setup: Two window boxes featuring, from left to right, carrots, green/string beans, tomatoes, and strawberry. The white PVC pipe has drill holes to provide water with a length of flexible tubing entering it on the left, supplying the pipe, and the right end of the pipe emptying back into the reservoir. A design issue with this simple setup is that the pipe is too high - it can easily erode un-mulched soil. In a better-designed setup, I would have the reservoir lower than the return so that the pipe can sit on the soil. The reservoir: Nothing fancy here. A 12v DC pump su...