Just spray them/mist them, just like you would any other epiphyte. You would be surprised how they grow.
I live in NE Mississippi. Several years ago I asked a Mississippi Master Gardner (probably around 2010 when I became interested in becoming a Master Gardener myself) why I never saw Spanish moss growing in my county. In 1995, I moved from the Mississippi Gulf coast, and Spanish moss was everywhere. Anyway, the Master Gardner said that it would not grow in my adopted county. Just too cold. and just too hot, and just too dry. Excuses, excuses, excuses. Well, I love a challenge so I took it upon myself to grow Spanish moss here. I "borrowed" a bag full of Spanish moss from the Pascagoula area and transplanted onto the limbs of my oaks. I would guess, over the last four or so years, that same Spanish moss has doubled and then doubled again in size. Now understand, this Spanish moss is "pampered". During the spring, summer, and early fall, while all my tropical plants are outside, under the oaks and cedars, when those plants get watered and fertilized, so does the Spanish moss. I am sure my neighbors think they have a crazy man living among them. Who every heard of watering and fertilizing Spanish moss?
Regardless, even after our horrifically cold winter this year, the Spanish moss continues to grow (at least twice as fast as the average, "wild" Spanish moss) and blooms profusely.
So that's the story behind my Spanish moss. I would like to tell you that I always knew Spanish moss bloomed. I saw my very first bloom last spring, but until I saw all the seed pods later in the summer and fall, I really didn't even know what I was looking at.
