As Davidinct mentioned the standard ProMix has Mycorise included but you can also order it with Biofungicides for a little extra per bale ($1.45 from my supplier). Both of these additives have research support for reducing pathogen organisms and the biofungicide can even boost production due to the benefit of the root colinizing organisms. These are similar to a whole new line of commercial products like TC-22, Rootshield, etc. Either way this new technology in planting media makes good sense. The opposite, very risky alternative of using any unsterilized material can lead to a complete wipeout of your seedling crop in a few days from soilborn pathogens. I would never,ever attempt to start seeds in soil from the garden. Your time is too valuable to risk the crop loss.

I use 511 regularly, where I work we provide machinery that focuses on cleaning grains, plastic extrusions, reclaimed sheet rock, reclaimed glass etc. we separate unwanted fines, or unwanted particle sizes from many various products via screening, air aspiration as well as other methods. This brings me to my question about gritty mix, I just happened upon some poly beads about 3/16 diameter, could this be used as the grit fraction in gritty mix? What I mean by grit is the the granite, or the inert fraction of the mix, the beads seem to be nearly inert, I process all my pine bark through a machine called a reel eliminator, it has various sizes of screens so I can dictate what particle size I want by varying the screen size, I always look for the bags of pine bark mulch that looks some what composted, and separate that into the fines I want, typical what ever will go through a 3/8 screen. I processed 4ea. 2.5 cubic bags in 10 minutes last week, sure makes it easy compared to my screens at home. I am wanting to make up some gritty mix primarily for some citrus trees in my greenhouse, these polystyrene beads have become plentiful and don't weigh very much. You guys are the experts and would love to hear your opinions, Thanks

i take it you do this because it is more cost effective? ~ a bale of peatmoss & a huge bag (which i have)of perlite is a better buy than a large, compressed bag of potting mix? ~ i can never *think* that through, cuz it's like comparing apples & oranges ~ sortof ~ for instance, i bought a *compressed* bale of pro-mix bx for $27 at a feed store ~ i dunno ~ is that a good deal? how the heck do i compare a *compressed* bale to a non-compressed bale? ~ and, boy o boy, it is really compressed ~ i almost have to cut out a chunk with a butcher knife! thanks for any insight ~ phyl

okay, i misunderstood. i thought i was reading about the gritty mix and turns out, it was for the 5-1-1. i added dolomite to my gritty mix and i just put all my succulents in that mix. what do i do? oh i dont want to lose them all..