A  Blind sheaths are those that do not bloom. There can be several causes, the most common being too little light. However, blind sheaths may simply be those produced by winter or spring blooming-type cattleyas that have not yet initiated buds. For example, many cattleyas will make up a growth with a sheath during the summer months, while the buds will not initiate until late autumn or early winter. Also, these types are subject to the sheaths' dying of old age, which can cause bud loss, as water condenses in the dying sheath and rots the bud primordia. For this reason, dying or yellowing sheaths should be carefully removed to allow continued bud development, though the inflorescence will have to be supported. If you think you have enough light (indicated by strong, upright growths) perhaps the sheaths are on winter- or spring-flowering plants. —NedNash.