You've got DHT11's pictured in you product photos. Don't use DHT11's for, well, anything.
I deployed ~ 100. After 8 months, only 35 still work. Even when they worked, the data was so variable they were constant trouble. Of the 35 that still work, about half are now giving useless humidity readings.
A little background. I made essentially exactly what he's selling as a garden monitor to place in a few dozen machine cabinets and motor compartments in a newspaper printing plant. Printing presses are hot, wet things and you can predict failure if things get too hot, or too humid.
So bare ESP8266 modules, OSH Park boards, and the sensors. After my DHT's started kicking the bucket two things helped:
1) Switching my software to only power my sensors for the time I needed to take measurements. (Once per 10 minutes). It does take some seconds to stabilize before taking the reading but the sensors spend most of their time off. I had to cut traces and add a little transistor to the boards to make this happen. That sucked.
2)I picked up some SHT71's and was able to bodge them onto the failed boards in place of the dead DHT's. All it took was a firmware update for my ESP8266. This was easy. I have not lost one since. I don't know how much 1) has to do with that.
As an added benefit, I've got my esp's deep sleeping during the off times (had to add one jumper wire to make this work... easy) and can now power them for weeks at a time with a pair of alkaline batteries.
For Sensor Comparisons, check out this site. Someone from a previous post on Hackaday turned me to it a few months back. Very comprehensive and is what led me to go with the BME280:
