The nRF24 is good for short distances ~10m. That distance can be extended because nodes can also be a repeater to the gateway. I'm using an RPi zero 2W for my gateway (which is also my irrigation controller.) Can you reach your greenhouse with WiFi? This may work for you. I'd look at the RFnano that has the nRF24 integrated. It costs about more than a Nano and nRF24 separately, but what you gain is no wiring and no wiring failures. I tried to used this moisture sensor and it corroded within a year. DHT-12 (digital humidity and temperature) can be off as much as 4°C per the specs and suffers from the same corrosion challenge. Speaking of corrosion, be sure to "paint" all your electronics with electrical lacquer sealer (but not on the sensors) You have to consider how you're going to power your sensors. I'm not a big fan of batteries because you have to jump through a lot of hoops to get the most out of the batteries. On the flip side, you'll have to run 5V to all your sensors. This is my [pathetic] attempt at a remote soil sensor