I haven't done this myself, but it should certainly work. You could try wrapping a bit of long brown sphagnum (New Zealand or Canadian, not gardener's' peat moss) around the base of the brome first. This stuff has magical qualities. Great Stuff is porous, and since one can grow bromes on tufa rock, I imagine it would work fine.
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Patty
Pahsimeroi, Idaho

Dendrobates: auratus blue, auratus Ancon Hill, tinctorius azureus, leucomelas. Phyllobates: vittatus, terribilis, lugubris. Epipedobates: anthonyi tricolor pasaje. Ranitomeya fantastica, imitator, reticulata. Adelphobates castaneoticus, galactonotus. Oophagia pumilio Bastimentos. (updated systematic nomenclature)