We found some wonderful step-by-step instructions on how to display your phalaenopsis orchid plant in a terrarium. There are orchid photos for each step of the way, too! But here are the basics.
Along with your orchid, you’ll need a deep glass container of any shape you like, river rocks, sheet moss, sphagnum moss, deer moss, paper towels, chopsticks, and orchid fertilizer. First, soak a few handfuls of the sphagnum moss in a separate bowl. You’ll start the terrarium display by carefully placing river rocks into the bottom of the container. You’ll want about two inches of the container to be covered with the rocks, which will act as a reservoir for the water.
Then, take a few flat pieces of sheet moss and place them along the sides, but leaving space in the middle where the orchid will eventually go. Before you place your orchid, remove it from its pot and gently rinse off the orchid roots, removing any dead, shriveled or unhealthy-looking sections. Place some of the moistened sphagnum moss loosely in between the roots, and the rest on top of the rocks inside the terrarium. Then place your orchid roots on top of them. You can adjust how high the orchid sits in the planter by adding or subtracting from the amount of sphagnum moss resting on the rocks. Add a small amount of sphagnum to the top of the orchid to cover up any visible roots, and then decorate the top of the container with the deer moss.
Then they recommend that you mix up a pitcher of quarter-strength orchid fertilizer and pour it into the container, covering the rocks and just barely touching the bottom of the moss. The moss will soak up the fertilizer and keep the roots moist without getting water logged. They say to add more water in a few months, but if your orchid seems dry, just add ice!