Orchid Trouble

[ashdoc]

I live in Zone 4a and have been having a terrible time trying to keep indoor orchids alive! I have tried with three different plants now all with the same results, here is what happens:

I get an orchid from the florist in the small cheap plastic containers. When the plant is done flowering, I pre-soak the bark in the transfer pot and move it on over. The pot I bought has holes in it and was specially designed for orchids. Everything goes great for a few months; I water it, add fertilizer, and make sure it gets some sunlight. After a few months though, the leave start turning yellow and fall off, then the stem turns brown and brittle not matter how much I try water it. I try not to over water, since I know orchids do not like that much.

Is it the humidity? Am I fertilizing too much (I usually try to do it once every two weeks)? Please let me know as I LOVE orchids and would like to keep them longer than one flowering season! Thank you in advance!