The location of my garden is on rock. On caliche. I could pick another
spot, but this one is convenient, and another would be much farther from the
house.

Digging down more than a foot or so hits caliche. This presents a problem
in that it is impenetrable by roots, and water runs off it.

I want to do a greenhouse, and do some raised beds, both for convenience,
and easier on the back. But what about the floor? If I were to frame up a
concrete pony wall, say one foot high and then fill the floor with good
composted soil, is one foot or slightly more enough for the roots of most
gardens? I could then use that pony wall as the base for a greenhouse. I
know I would have to watch the water so as not to soak the soil.

TIA

Steve