hi G,
I would suggest that the Base [ House monitor] HC12 be powered 24/7, they use very little power in the RX mode.
So it could be listening 24/7 for any data coming from the Remote [Green house] transmitter.
You could still time select the Remote TX data transmit interval and/also any 'alarm' conditions as they arise. Timed TX intervals will also reduce Remote battery usage.
The HC12 is advertised as 1000mtr range, for that I would recommend a HC12 dipole antenna at the Remote TX end.
If the 200 mtrs distance from the Allotment remote is 'line of sight' you may be able to use the onboard 'coiled' HC12 aerial, its worth a try.
Keep the Baud rate at 9600 and use max power setting.
You may find other users on a particular frequency channel, bit of trial and error required.
For the TX data I would suggest that you transmit the message as a 'cvs' [ comma separated variable] string.
The Green house for example say, A,+12.3,57.2,11.8,crlf
Thats
ID= A
Tempr
Humm
Voltage
CRLF
The Allotment would be B,12.3,57.2,12.9,crlf
ID=B
By using cvs format you can paste the recorded data file into a Spread sheet program, for plotting/analysis.
I would set the TX interval to say 1 hour, in that way you could do an hourly in house monitor check.
E
My data string:
A,+26.2,21.9,4.955,09.74,010111,+00.0,12:45:36
I add the indoor tempr and time at the end of the recorded string, using the PC log