Dee Dee Lozano asked about the instant orchard --- I referred to pomegranates as an instant orchard because they often produce in year one and by the third year, production takes off. Most fruit takes a lot longer to give a significant yield. If I find that mine winter kill, I'll grow a few in a greenhouse and turn the hillside over to grapes which always work here.
John Elliott wrote:You mean like Phoenix? Las Vegas? Places where entire yards are covered with rocks with a tree here and a cactus there?
In those places, it doesn't make the root zone warmer, it keeps soil moisture from evaporating and keeps the root zone cooler. You pick up a good size rock, and the dirt beneath it is damp from the last watering.
Rocks do have a tremendous heat capacity, so down a few inches, the soil temperature is very moderated. (You would know this if you were a desert tortoise or you had one as a pet).
There is also the factor of rock color to keep in mind. A very light, almost white granite boulder is not going to get as hot as a piece of black lava rock. You can soak up a LOT of heat for the greenhouse if the sun is shining through onto some black lava rock.
What specifically do you want to do?