The first thing you need to do is find a suitable branch for your tree. You can go to a nursery and pay for a mounted "driftwood" type branch, but I think it is more fun to go for a walk and see what you can find right around your back yard or in the neighborhood.

A branch from a live tree will usually make a good orchid tree.
I chose a branch off of my Sycamore tree. Try to find a branch with a rough surface. A branch with smooth surfaces will work, but are not as good because they do not provide the orchid roots something to cling to.
The size and shape of the branch is entirely up to you. It can be as small as one foot or as large as 5 feet!

Of course, if you are in your neighbors yard, ask first before taking any of their tree branches ;-)

These are the items you will need to assemble your tree. You can obtain these items from your local hardware and gardening center:

Sphagnum moss - to cover the roots and help give the orchid moisture

Bucket or container of water - to soak the Sphagnum moss

Now that you have a branch and all the materials assembled, you need to select some plants to decorate your tree.

There are many different types of epiphytic orchids (orchids that are found naturally growing on other trees) that you can use.

Depending on the size of your tree, mini Cattleyas, Dendrobiums, Oncidiums, Phalaenopsis, Epidendrums and my favorite, the little equitant Oncidium orchids will all grow on your new tree.

Avoid fast growing orchids like large Cattleya hybrids some types of Oncidiums, and Odotoglossums because they will overgrow your tree very soon.

The easiest thing to do is to find out how fast you orchid will grow. This will help you decide whether to use a particular orchid or not. Don't be afraid to experiment and remember orchids don't all grow straight up like we tend to grow them with our sticks holding them upright. Dendrobiums and Epidendrums can be hung dangling from the branches in the same manner they grow in nature.

Now that you have everything ready we can begin building your tree.

First place your moss in the bucket of water an let it soak to make the moss easier to handle.

Attach your branch to the wood base by drilling a hole in the base large enough in diameter to hold your branch firmly in place.

To get a firm fit, make the hole slightly smaller than your branch and then trim the branch to snugly fit the hole. Or make a cross stand like you see holding the Christmas trees. Trim your branch as you think necessary to achieve a nice balanced look. Position your plants one at a time and get the feel of where they will look the best on your tree.

Once you decide where you want to attach your plants, prepare and attach each plant starting at the bottom of the branch.

To prepare a plant for mounting, you want clean, healthy orchids.

Remove all of the old media from the plant.

Cut the dead roots all the way to the base of the plant and trim live roots and growth.
Dust the areas that you have cut with sulfur to help prevent rot and fungus.

Remember to sterilize your scissors before moving on to trimming each plant to prevent spreading disease from one plant to another at this time you can make out the tags for each orchid.

If the orchid is already mounted, trim off as much of the existing mount as possible or carefully remove the orchid from the mount.

Roots grown in pots will more than likely not succeed as aerial roots, but new roots will grow and replace them, don't trim off all of the roots because they will help support the plant and they will supply nourishment until the new roots grow.

Once you have your plants all cleaned and ready to mount you can begin the next step.

Attach some of the wet Sphagnum moss around the branch using the green plastic coated wire where you plan to attach a plant.

Place your orchid on the moss with as many roots as you can position on the moss and cover the roots with more wet moss.
Wrap the entire area with fishing line.

NOTE: You can temporarily fasten the orchid and moss with the green wire. Make sure the plant is firmly attached to the branch.

Lastly, attach the label on the branch or attached to the orchid before going to the next one.

Continue mounting your orchids until they all have a home on your tree.

When your tree is completed, spray it well with water and place it where it will be living.

Your tree should be sprayed once a day if you live in a dry area (in a greenhouse, twice a week is sufficient).

Add a weak solution of balanced fertilizer to the spray once a week. If your tree is located in your home, place it in the shower once a week to give the plants a good soaking like a tropical rain storm. The water should not be cold or warm... think of a summer rain in Hawaii or Florida.

If your tree is going to be a focal point in your home, place it in a decorative tray and add colored gravel to cover the stand, or place it in a decorative flower pot filled with gravel.

Congratulations!
You have just completed your very own orchid tree.
Sit back now and watch it grow and bloom for you.

Stop by my articles available at this site and learn more about potting, re-potting - and I am sure you will be surprised at some of the media that can be used to keep your orchids happy and well.