Pro mix BX, idealwater content%

with a sphagnum peat moss base, you want about 50% of volume to be perlite (#2 USA standard), vermiculite (coarse, sometimes "#3" if not mistaken) or similar drainage amendment. This will give you an optimal gas:water mix in the medium. I'd recommend adding vermiculite, as it also provies some available Si to the plant over time. I use hp or bx each year. I mix in a 4cu ft bag of coarse vermiculite with their 3.8 cu ft compressed bale (~6-7 cu ft uncompressed) Expect to lose a bit of volume when you mix such things... 4+6 will equall less than 10 cu ft when done. the medium fills gaps between teh vermiculite or perlite etc. the less fine it is, the more profound this effect is. BX comes with ~15% perlite .. if you want to be more exact, apply some algebra... "They" say you get 7cu ft from a bale, but i think it's closer to 6. That impacts the math a bit. If you buy it loose, that makes it less of an unknown... 2.8cu ft loose is 2.8cu ft. HP bale has ~25% perlite. I've used both and see absolutely no difference between them -- given my additions of perlite or vermiculite to get near 50% of volume. You don't have to be exact on this stuff... close enough is good too. whether i buy bx or hp, i mix in the same 4 cu ft bag... i'm a little over with hp and a little under wiht bx, if i recall. These suggestions come from an old bubgee video, fwiw. think the 2+ hour one about maximizing yields on youtube. https://youtu.be/JwtkHxv_3pU?t=1401 I pasted the link at the specific time stamp, but that whole video is awesome. He's got a ToC with links in the description to skip around without watching 2.5hours. Unles there's a huge difference in price locally, i'd suggest vermiculite over perlite.. around here they are the same price most of the time.. ----------------------------------------------- BX tech data:https://www.planetearthgardensupply.com/content/Tech%20Data%20PRO-MIX_BX_Mycorrhizae_13478.pdf HP tech data https://www.domyown.com/msds/PRO-MIX_HP_MYCORRHIZAE_Technical_Bulletin_2023.pdf