Bob C,
Thanks for the reply and the detailed info.
I've never done this but, a small wood chipper could be used to reduce the large chunks to make uniform sized Bark Mulch for the potting mix.
Rafael,
There is a bit of confusion with the technical term "soil porosity" and the adjective porous.
The smaller the mix particles, the larger the volume of air spaces, this also increases water holding ability, and increases soil porosity. Porous and porosity is also used to describe the larger air spaces and air volume held in soil which is partly where the confusion arises. When I first started making custom potting mixes over a decade ago, the terminology was confusing, so I made the distinction between Porous or quantity of small air spaces and Aerated or quantity of large air spaces, because its easier for me to visualize, one is fine grained and the other is large particles. Its the difference between a 32 oz. container of Peat and a 32 oz. container of Coarse Perlite, the peat container will hold much more water because it has higher soil porosity.
ProMix-HP is refering to the increased Aeration of the mix caused by the additional Perlite, but technically they are actually decreasing the soil porosity, by decreasing the quantity of small air spaces. Hope this helps.... Many other manufacturers make the actual distinction between soil porosity and aeration in their descriptions.
Tim,
Thanks for posting and sharing your mix recipe and results.
Congratulations and Good Luck with the new farm...
That website had been linked in another topic, and I had planned on liking it in this topic.
I use the same brands of Bark and Perlite but use the Premier or another Canadian brand Peat Moss
I'm also looking at locally available ingredient alternatives which is why I'm trialing a few Sand-Gravel Mixes (with a compost/mulch top layer) that were successful in the past.