Lady's-slippers or Paphiopedilum grow best in bark media. The air humidity should be more than 60%, especially in the morning and in the evening otherwise, you risk the attraction of thrips and red spider mites. Studies keep repeating that Paphiopedilum like chalky soils. Photos and research projects in natural habitats show clearly the plants grow in humus nests on rocks and trees. Thesis, unlike the chalk rock have an acidic pH value, however, lady's slippers like calcium in the medium or in the fertiliser.
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