Evan, if you are mounting bromeliads on some sort of wood, here is what I do for all my mounted plants, and I have many dozens mounted, from staghorn ferns, bromeliads, tilladsias, and orchids.
1. Decide where you want the center of the plant base to be. Let's say the base (root end) of the bromeliad is 4" in diameter. Drill four holes, using something like a 1/8" drill bit, two approximately 3" above the center point and 6" apart and then two more 3" below the center point and 6" apart. So now you have a 6x6" square with holes in each corner.
2. Take a handful of long-fibered sphagnum moss and place it in the center of that square and then place your bromeliad (root-end base) on this mound of moss.
3. Now its time to thread your tie-down material. I have started using florist wire, the green coated kind, but you can use any plastic covered wire, monofilament fishing line (about 10 lb. strength), or even cotton cord to tie your plant down. Whatever you use, starting from the rear of the mount, thread it through one hole and thread it through the hole that is catercornered (diagonal) to the first hole. Do the same with the other two holes. You can use two pieces of wire or one piece to accomplish this. Now you have crisscrossed the base of the plant with wire/line. Leave plenty of slack in the wire for the next step.
4. You now want to cover the base of the plant so that the wire/line will not cut into the plant. I use coconut fiber for this but you could use the same sphagnum moss as you used behind the plant. Just cover the base of the plant in some (protective) material and then its time to cinch the wire/line in tightly across the plant base. All your wire/line should be in the back of the wood mount so just pull the ends tightly and tie everything together. Your plant should now be firmly tied down.
5. If you are mounting a tall plant (bromeliad), you will want to support that upper part of the plant. I drill two more holes about 1/2 way up the mount and adjacent to the side of the plant. I then thread another piece of wire/line through one hole, cross over the plant, thread it through the other hole, and then gently tighten and tie the two ends together. You don't want this so tight that it cuts through or strangles the plant but tight enough that the plant won't be able to tip over.
Feel free to contact me if you have questions.
