Phrag. grande repot inquiry

[Epiphyteme]

Recently picked up a Phragmipedium grande from a local orchid nursery, not a big fan of the condition of the I’m pretty sure what once was pure spaghum it was in . Just ordered some bark, spaghum, perlite and charcoal to mix up something new for it. My question is it’s not in spike it has a few new growths that seem to be doing alright, is now an acceptable time of year to repot ?

My reasoning :

The mix is on its way to being sour or is
It has to have been AT LEAST a year since it was repotted... I’m sure longer by a good margin
Two days after getting it home fuzzy whitish mold was on the surface , it has plenty of air flow from the fans in the room I cleaned the surface but I’m not a fool to think it would go away that easy

Sound reasonable ? Not much if any Phragmipedium experience.

[bethmarie]

Repotting sounds like a good idea. Old mix is the arch enemy of Phrags.

[Epiphyteme]

Thanks for the input , that being said I’ll repot it in the new stuff once it arrives and it can go behind the catasetums on the brighter side... and the side by the zygopetalum I can put ???? Who knows haha . You recommend anything like hydroton or perlite on the bottom for drainage ? Perlite will be in the mix but I ordered a1/4 ft I could give it a decent bottom layer if it would be advisable.

[estación seca]

Layering different things in pots does not improve drainage; it impedes drainage. Water doesn't flow well past drastic medium interfaces. Pick one medium and fill the pot.

Phrags like a lot of water, which is why the medium doesn't last long.