Thunia species are native to the Himalayas where they grow long pseudobulbs during the monsoon and then drop their leaves once the dry season starts.
We have seen Thunia alba growing on the side of mossy boulders in shade near the road from Kalimpong (West Bengal) to Gangtok (Sikkim) at around 500m altitude where they will experience very little rain from Novemeber to February and constant wet from April until September.
At school we put the Thunia pots up on a shelf where they will be completely dry once the leaves have dropped in November. In February we repot into fresh compost and slowly introduce watering avoiding getting too much water on the foliage until the plants are growing strongly.
It is fair to say that there is some confusion over the naming of Thunias as once seperate species Thunia alba and Thunia marshalliana are now considered synonymous.