For those who haven't heard of a Bollopetalum (note spelling) it's a cross between a Bollea and a Zygopetalum. Bollopetalum Midnight Blue 'Cardinal Roost' (note correct capitalization and punctuation) is Bollea violacea x Zygopetelum B. G. White.
As they are a Zygo hybrid, Zygo culture applies.
Here is a Zygopetalum Culture Sheet that looks pretty competent. And here is one pic And another