The correct answer is "when it needs it", and yes, if the plant has not
increased significantly in size, going into the same size pot is fine.

As to what defines "it needs it", the primary issue is the medium getting
too compact, so it holds too much water and suffocates the roots.

Another thing to consider is mineral buildup - if you haven't done a
reasonable job flushing, the buildup will become too much to conveniently
redissolve, so fresh medium will be in order.

Or.....you can consider semi-hydroponics and never change the medium, just
adding more as the plant gets bigger.

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!


"Jane" wrote in message
...
I have six healthy phals.

Is it a good idea to change the potting medium even if you're not
changing the pot size? How often should the medium be changed? I
don't want to do it more often than necessary. That stuff is pricey!

I use a combination of moss and bark chips.

thanks