I've found they do best in a leafy mix, well drained but moisture-retentive and with some grit added. I've only had them in pots as my present garden is very dry overall but we've had a lot of rain this year, even last night, heavy rain followed by hot dry winds, most unsummer-like for east coast NZ. For the first time ever, Mec. quintuplinervia is thriving and increasing - in a big pot, kept cool and damp.
Sadly, in my experience Mec. punicea has always been monocarpic but it does give good seed which, if sown fresh, germinates 8 months later.