I would have gotten that Phalaenopsis just for the leaves. Who cares if it ever blooms!
I grew orchids in several terrariums for a few years but, eventually gave up on the idea. Don't cover the terrariums and you probably won't have a problem with air flow (I started with fans but took them out). The thing that finally ended my terrarium/orchid experiment was salt buildup. I planted all my orchids in sphagnum moss on a gravel base (out of their pots) and they absolutely loved it! But, even though I fertilized like once a year and then flushed and drained, disaster struck.
My gut feeling is the slowly decomposting sphagnum moss messed with the chemistry - the plants acted like they had salt poisoning. I think that because the one terrarium that lasted the longest had live moss.
So, what I learned from this experiment is keep your plants potted in their own pots. BUT, the reason I set them free in the first place is the plant roots had left their pots and rooted into the base medium and I felt the pots were strangling them. Maybe the next lesson learned is don't treat your orchids like pets.
I am interested in knowing how your terrarium works out for you. Please come back to this thread and keep us posted.
