My oft spoken modified proverb: “The best time to plant a tree is 20 years ago, the next best time in 1 year from now”
Laying down a mulch of shredded wood at least a year before planting a woody species will create an ideal soil habitat for the plant whether it be a bramble, shrub or tree. Plants uptake nutrients via a symbiotic relationship with mycorrhizal fungi. A layer of woody mulch well before planting facilitates the fungal dominance in which woody species thrive as well as invigorate soils with nourishment from the decaying wood.
Plus some of my trees planned for next year need a sulfur application to acidify the soil lowering it to the ideal pH for that species. Sulfur needs months to be broken down in order to actually have an effect on the soil.
My process was as follows:
Weed wack all plant matter to the ground, rake out the clipped plants if they are significant
Apply the calculated amount of sulfur (tables can be found in this post)
Return any raked clippings (if applicable)
Lay down cardboard or paper to smother the existing turf. This biodegradable barrier will breakdown to humus given time!
Pile on as much mulch as you can spare
Come spring time, your back will appreciate the more workable soil (although I don’t recommend amending the soil or loosening it mechanically by digging an oversized planting hole. See here)
Removing most of the above ground vegetation:
The clippings are then raked out, sulfur applied (for the sourwood planting sites), then the clippings are returned.
Cardboard or sturdy paper (paper grocery bags in my case) are laid down to smother the vegetation then mulch is piled on top.
The [almost] finished site looks like this:
More tips to ensure success with trees
Where to find mulch for woody species
How to think like a plant to be a successful cultivator
How to think like a plant to be a successful cultivator part 2
Mulch Matters 2: Different Types of Mulches for Different Types of Plants