B. rajah is a highly ornamental rhizomatous species native to Malaysia. It traditionally is found growing on rocks alongside streams. However, I grow mine in a terrarium-type setting in a peat-based potting mix to which I've added 30% extra perlite. As is so often the case with Begonia species such as these, I am careful not to overwater.
Seems to be easy to grow - but best in enclosed of otherwise humid space.
These are currently in 2-3" pots.
|Int - Warm||Low - Medium|
Int - WarmMalaysian species which does superb in a terrarium-type setting