For those of you into your veg growing you will know that covering a veg bed in black membrane for a few weeks before planting can raise the temperature of the bed and give the seeds a better chance of germination. And that putting black containers filled with water in a poly tunnel or green house can adsorb the heat from the sun during the day and slowly release it during the night to help prevent the temperature dropping so much overnight. Well, working on that theory I decided to try and experiment.
I had to paint the concrete floor of my small poly tunnel to give it some extra protection from wear and tear. So if I paint it black will it work on the same principle of adsorbing heat from the sun during the day and release it at night. Time will tell.
Achies Farm 
Certainly sounds reasonable! Hope you have a thermometer that registers and show a difference in a positive way. Good thinking!
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Yes, I have max / min thermometers in both poly tunnels. Going to be interesting to see if it makes a difference. Either way it’s a good job done 😊.
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