channel
The slice of the radio band a Wi-Fi network uses; neighbours on the same channel share airtime.
A Wi-Fi channel is a frequency range within a band (2.4 GHz channels 1-13, of which 1, 6 and 11 don't overlap); networks on overlapping channels contend for the same air.
Examples
In the 2.4 GHz band channel n is centred at 2407 + 5n MHz, so channel 6 sits at 2437 MHz, only 5 MHz from channel 7.
An ESP32-S3 or ESP32-C6 uses only 2.4 GHz channels, so a 5 GHz-only network is invisible to the greenhouse node.
See also