I was wondering if I’m getting this wrong with my technique and soil mix? I till the area I want to plant in first breaking up the ground and removing some dirt. I think mix in compost, pine bark much and soil conditioner into the area with the natural soil. Then dig the hole to size then putting a little more compost, soil conditioner in mix then plant the maple. Basically I’m trying to prepare the area around my potting hole too. Can I just mix pine bark mulch, soil conditioner, compost and then using store bought potting soil for planting maples in pots? It just has to drain right?
Personally, I think this method is a bad idea. I think one should simply plant in the soil you've got and then mulch over the drip line and a bit beyond, keeping it a away from the trunk base. Don't mulch any deeper than 4 inches simply because roots need oxygen to live and grow. Extend the mulched area each year as the canopy expands - the active root tips are in the region outside the drip line. In a a few years, the mulch will have begun decomposing and will be enriching and loosening the soil beneath. Refresh the mulch inside the drip line from time to time. When you plant Japanese maples, it is better that they be on a mound (a rounded knoll like a pitcher's mound) than in a low spot. Water will collect in low spots and may pool which will mean your trees roots will literally drown and so too will your tree. 'Mounding' assures drainage and assurance against this happening, especially if your ground is a high clay soil.
This article outlines general principles about planting trees which I think would also apply to Japanese maples. Problems with Planting Trees
@Connor Sullivan, this can be a hot topic on the forum Connor. We all have our methods that we use, some amend their garden soil and some don't. I am in the former bracket. But the latest science says 'not to'. I will comment on J @Osoyoung regarding mounding and mulching though, that advice is 'spot on'. I do this with all my trees. Regarding pots, do have a look at this thread Transplanting maples in Autumn/ Spring