Often in the past I would take a new plant out of it's 'too small pot' decide the moss is still good, add a layer of fresh moss around everything and drop it into a larger pot. I'm not the only one doing that, many members of my society and even some nationally renowned growers do this.

I'm in the finishing spasms of re-mossing all the cool plants in moss and saw things I didn't like. When unpotting such a plant, it's immediately apparent that there are 2 types of moss. The 'new' moss is now 1 to 2 years old and needs to be replaced. The 'old' moss in the center is even older and resembles a 'Death Zone'. Deteriorated powdery or mushy moss with old or dead roots while the new roots are all in the periphery.

I think all the moss in a pot should be of the same age so one can accurately judge when it's time to replace it. From now on when a plant needs a bigger pot, I will remove all the old media and have the entire plant in the same quality of whatever. For large plants, say a Pleuro in a 6" net basket moving up to a 8" or 10" bucket, that's lot of work but worth it. Teasing the old moss out of a densely packed root ball is a labor of love.

Nick