What rocks trap and hold heat best?
November 11, 2011 6:38 AM Subscribe
What kind of rocks collect, hold and release heat best?
I want to use some rocks in my little pop-up greenhouse to collect heat from the sun during the day and release it at night to keep the plants warmer.
The plants in question live outside most of the year at my Zone 7 home, but I can't bring them inside during the winter because the cats destroy them. There are some geraniums, a spider plant, two big hibiscus [hibisci?] and a few other generally green things that I've inherited but can't identify.
Are there particular kinds of rocks that would work best t for this purpose? Dark ones, right? Beyond that, I have no clue. Rocks aren't my thing, and I'm only barely scraping by with these plants. :)