depends on the conditions in your growing space / water scedule

The moss is not bad as long as the roots look good. If the roots do not look good, then it should be repotted in bark. Orchids growing in moss should be watered with good water. Hard water minerals can accumulate in the moss and kill the plant.

I agree with Tolumniamatt about the moss and how to care for orchids in moss.

I would like to add that I generally repot newly acquired orchids, especially if they are from a big box store. I repot so I know how old the potting medium is and to make sure that I can care for whatever it is potted in.

Ditto what tolumniamatt and Greencurls say. Moss can be tricky to grow in if you are inexperienced. Bark is a much better medium to start with.

The choice between moss or bark is a false choice. You can mix and match in any proportion to get the best of both worlds. When I got my first orchid just a month ago, I mixed my own mix consisting of 3 parts pine bark >3/8ths of an inch, 1 part coarse perlite >1/8th of an inch and 1 part long strand chilean sphagnum moss. Bark drains instantly, requires more frequent watering and is more tricky to determine when watering is needed, but creates air pockets between the strands of moss. Moss retains more water, so less frequent watering is needed, but it can suffocate the roots when compacted and if not allowed to dry out. Perlite holds some water in the pores, but is mostly to create more air pockets. There is no hard science to these ingredients or to the proportion (truth is I had the coarse perlite, so in it went almost exclusively because of that). But I definitely wanted a mix, as any one of these or any other ingredient individually has serious disadvantages from what I have read.

I've also read that for orchids growing in moss-heavy mixes or in 100% moss repotting into a mix that contains at least some moss is beneficial to minimize repotting stress. Then if you really do not like moss, you can repot into something else at next repotting.

If you do use moss, water generously till the water drains freely every time - this minimizes salt accumulation in the moss.

Finally, the root thickness and structure play a role. Thinner-rooted orchids typically like finer mediums and thicker -rooted or orchids with more extensive root structures like coarser mediums.

This post was edited by greentoe357 on Wed, Sep 18, 13 at 2:28