Mulch in potting soil.

Looking for inexpensive potting soil to grow woody perennials that will eventually be planted outdoors. I've been doing a lot of research and it seems like a lot of nurseries use mulch in their mixes. A mulch producer in my area sells a mix of %80 triple shredded aged (two years) hardwood mulch and %20 leaf compost. This seems pretty similar to some recipes I've seen. Does anyone have any experience with this? Am I headed down the wrong path? I'll post some photos so you can see what I'm working with.

I used 2 year rotted hardwood chips in my batch of home potting mix last year, with some added leaf mulch. Dubious results.

I think it lacked nitrogen as many of my seedlings lacked vigour and colour, and I had loads of weed seeds pop up. The chips had got hot when first composting, but over 2 years seeds had blown in. This year I have gone back to bought bags of potting mix for delicate seedlings.

I'm mostly using this for larger rooted cuttings with pretty good root structure. Do you think top dressing with worm castings would be a good idea?