I do not know English well, so I will use Google translator, sorry if there are any mistakes.
I tried many times to make a greenhouse, but nothing efficient came out.
The best result is 40% of all blocks with an effect of + 5 °C from the greenhouse. An area of 121 blocks minus 9 blocks is a source of water and 112 blocks.
And only about 45 blocks with an effect of + 5 °C from the greenhouse. Maybe you need to use other blocks or some other trick ?
Thank you in advance. You will help out a lot.