Okay- its been exactly a week since I decided to go rouge with the bags and buckets of NOT on-the-list substrates and I've learned some things.
Mixes that are mostly non-organic- while they drain beautifully- compress really nasty and hard. We're drowning in NY with 14" of rain in the last 12 days and that will really give you an idea of a long term outcome. If I can't press a bamboo skewer through a seed cell, its not going to be nice for new root development, regardless of moisture content and appropritate drainage.. If it feels like concrete- doesn't really matter if its wet or dry.
SO Im wrong before I even planted anything, in every way except 1/3 each perlite, peatmoss and grit (sand, turface, fine aquarium gravel were the same- however, HD fine gravel was the worst and should be used for masonry applications only- its very angular and locks into place after it settles so the drainage is very poor and it compacts so tight nothing will get through it. I think its meant to do that so weeds cant grow in cracks-very efficnt product.
I didn't want to buy more brand name cactus mix- $6 a lb for "special" dirt/organic mix is not okay in my book when I know Its 3/4 sand, perlite and peat, at a minimum. I investigated it, and it seems like the addition to peat pearlite and sand is really really small wood chips- which makes all the difference. I was unable to find superfine wood chips without screening them myself- but I dug around and found something to lighten the load.
THe one thing that made my mix manageable, given I don't have access to very fine wood chips and wont pay top dollar for it was pulling apart then cutting short the coco fibers from last years Dollar store hanging liners- I pulled it apart first then balled it up and cut it into ~1" lengths that I mixed into my various mixes and ended up with a much more manageable flexible soft substrate that I feel really good about.
I did try trimming short lengths off the edge of the coco liner as is. That doesn't work- very clumpy and doesne't ever come apart no matter how much you mix it. You have to pull it apart first and when its a nice airy mess you can cut it with a scissor and mix it in.
We"ll see how many hundreds of dollars of plants I kill to save $6 of specialty soil - but at least we'll have data!
