What is the best planting medium / mix for Orchids?

[Cactuseed]

My 2 C's & i realize off topic:

Repotme sells quality yet very pricey mixes. If you want to save some money here's my DIY repotme mix :

1 - fir bark. get it from a pet store that sells it for reptiles. 4 bucks for a gallon bag
2 - garden store (hd, lowes) get some perlite. 3. while your there get some lava rock.

wash the lava rock. mix at 4 parts fir bark to 1 part perlite, 1 part lava. put in a bucket and pour boiling water into it to kill bug larvae and stuff.
Plus depending on the orchid I add some moss.

Also i do not recommend 'miracle gro' orchid mix. I had some given to me and it is basically potting soil. unbelievable