"JoeSpareBedroom" wrote:

The other issue is that most plants don't want the soil to be hot. If the
plants are in the sun, the pots will be at least as hot as the surrounding
air, sometimes hotter.

That's not true. Some pot materials may heat up but so long as the
soil is moist there will be no heat build up around the plant's roots
whatsoever... as the water evaporates the soil will actually cool.
Were your fercocktah theory true plants wouldn't survive, and of
course would turn science on its head. The main purpose of clay pots
is that they absorb water and permit air to penetrate, they act like
air conditioners. What you never want to do is to place potted plants
near any wall that reflects the heat of the sun (if you must better a
dark colored wall that absorbs heat than a light colored wall that
reflects), radiant heat will cook the foliage even though their
watered roots remain cool.

Growing vegetables in pots is very easy. Try to stay away from
plastic and metal pots, better to use clay and wood. Stay away from
those resin pots that resemble concrete, they're plastic. Thick
walled concrete pots are not very good either, they are too
impervious.