it is best to plant them in black plastic pots but not necessary. as for the pea gravel it depends on where you are ive never had a single burn on my plants but it doesn't get a 100 or over is if so rarely, the best way to protect them is just make a plastic ring out of a soda bottle or water bottle and place it around the trunk . just so the hot gravel isn't touching the tree . and for more heat set them on pavement or next to a brink or block building

Thanks for the response. So the gravel will help with heat?

yea have u ever touched a hot rock after the sun goes down it retains the heat especially if you live in cooler climates

you can put white rocks around the stem and then the darker rocks outside of that. Bill