I believe it's also called pine fines. I use it in the beds as mulch to help with weeds and keep the soil from drying out too quickly...
And as I write this, I think I know where I went wrong!
I was mixing about 1/4 soil conditioner with 3/4 soilless mix, and sometimes adding plain potting soil when I could find it. (No fertilizer or moisture control.) When I repotted them, I used that mix in the bottom 2" of the pot, then added 2" of Daddy Pete's Raised Bed Mix, and topped the rest with the soilless mix. So I'm probably closer to 4" of the soilless.
Someone had mentioned the roots want moisture, but the rhizomes don't, and I thought the layering made sense. Daddy Pete's is a mix of gypsum, sand, pine fines, perlite (which is great!) and aged cow manure (which is risky) but I'm not using a lot. I'm keeping an eye on them and so far so good. And with all the rain coming, we've made room in the garage for them to ride out the storm. William mentioned keeping excess rain off helps with the rot issues too.
