Hi I have heard it many times. And whilst I have had some Drosera self seed into the odd Ping pot (the only place I use vermiculite) and they seem to do ok, I wouldn't risk my Heliamphora with vermiculite if there is the slightest chance that it is or can be toxic to them. After all is it worth the risk?
I use vermiculite on all my CP ,without problem , for me perlite is more harmful on acid plant ( not here on heliamphora).
for the heliamphora it seems to me that the problem is the substrat change.
if you receive yours heliamphora with sphagnum and perlite use always this substrat , it is a hydroponic soil , the roots are long and clear often very brittle , in blond peat + vermiculite rather little , more dark and more resistant. with a lot of 'radicelles'
for me the problem is here , a hydroponic root is too fragile and no adapted with others substrats.
I also use vermiculite with most of my cp's such as Nepenthes, pings, some bladderworts, and some drosera species. I do however, soak the vermiculite in purified water for ten min or so to make sure to rinse some of the inputted fertilizer out (as with the miracle grow brand of vermiculite).
okay, I feel better about the mix now. My vermiculite comes with no fertilizer added in and I planted them quite delicately. So from the sounds of it, as long as the sensitive roots can adapt I should be okay. Thank you for your input everyone!
I don't know about toxic in a chemical sense. I haven't used vermiculite in over 20 years, mostly because I always felt it got soggy under "classic" CP conditions. I'm not sure I see that difference in Heli roots based on media; to me seems more like that's age of the roots. The tips or newer parts are clear, or even pink close to the main stem on some plants, but darker further down. I'm lazy about washing perlite, too, but I can't see a chemical issue with it (assuming no vertilizer, etc.) since it's rock popped like popcorn via baking. I prefer lighter, airier media kept moist by flowing water, so I use NZ sphagnum + perlite. I guess that's kind of hydroponic. I just take the plant in the sphagnum plug it comes in and add it to the mixture as is, after (now) spraying with benomyl as a preventative measure. I would use live sphagnum if I could keep it from breaking down and getting mushy beneath the surface. I've used basic peat/sand/perlite as well, but for smaller plants I've noticed I like something less dense.
So, how's everyone's orders doing? I've got growth on everything, even the expensive H. uncinata and the tempermental (for me) H. hispida. There's still a long way to go, but this is a better start than usual. Fortunately, we've only had a few days consecutive at most warmer (but not riduculously warm) weather; the real battle will be over the next few months (until ~mid- to late September).