What I do is lay out a little tarp next to my hole, dig the top soil out and lay that on the tarp, eventually you will reach clay. Keep on digging and toss the god damn clay over your back or where ever, just scatter it around or someone might see that fresh pile of dirt on the ground. Once you get down far enough about knee deep or so (bout 2 foot) you're ready. Take your bought soil, soil amendments and that top soil on your tarp and mix it all together then throw that shit back in the hole.Nothing wrong with using a little native soil unless it's garbage from being strip mined in the past. Come back in two weeks and plant your plant. Don't plant it the day you dig your hole or you will be sorry. Some little critter will come by and dig your shit up and you will be EXTREMELY pissed off.