You might also try a mix of fine treefern fibre, chopped sphagnum (not sphgnum peat!) and medium perlite in equal portions. Moisten this mix before using it for repotting, but it will stay light and fluffy, provide a lot of air at the roots, and stay quite moist. If you use unglazed clay pots, you will provide further transpiration at the root zone. Good luck!
Adam
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