The bags help keep the sourounding soil from sucking all the water out of your hole.
It helps alot where its super fuckn hot.
This year im using 5 gal buckets buried so i can set em up with dirt an animal cage an plant all ready to go.
THen just drive by an drop em in my spot its quicker.
I am also interested in this. I am planting in very sandy soil and the summers get hot and dry. i am worried about drowning/rot and root constriction though.