Outdoor Growsite Prep HELP

Hi, I am planning on transplanting some month old bagseed plants into my backyard alone with some mazar i shariff around may. I live in new england and the plot which is most accessible to me is in the midst of some large pine trees as well other greenery. As I dug into the soil the other day it was about 2 inches of pine needles and then I came across a grainy dark very rooty dirt which gave way to a rocky clay like substance. Will the roots be a large problem in restricting the water to my girls? Should I try and dig out the area and place in my own few feet of soil or try to prepare and make do with the existing soil? It's not a matter of finding a soil recipe that will work, I've foudn that, I just need to know if If roots of existing plants will thwart the growth of mine.

nah, the roots of existing plant won't thwart your efforts. Ever tried to grow more than one plant in a container? You'll be fine. I'd dig up as much of the clay though, and put in your own soil. Your plants will have a hard time breaking through that stuff.

Pine needles are a problem and will require you to PH the soil. Here's some links you may find useful.
https://www.rollitup.org/outdoor-growing/47236-sublimes-sublime-guide-guerilla-growing.html

http://marijuanagirls.com/MarijuanaFree/MarijuanaGrowGuide.html