The Powdery moss as you put it is probably what I have. I bought mine from my work it is commercial moss used for soil amendment. So far to date I have used it without problems. Its to late in the season for me to change up the composition now. I will have to wait until spring for repotting time and get the new moss then.
I am glad you are aware of the timing issue

Do you have deciduous trees: [Outdoor, Loses leaves, Needs dormancy]
Or tropicals: Serrissa, Ficus, Schef, ect.?
While you are correct that it is too late to repot a temperate tree, Tropicals can safely be repotted at any time with good aftercare.
[Though obviously good aftercare should go without saying...] If you do have to wait until repotting, Please Be aware of your trees watering needs. Knowing when not to water is as important as knowing when. I'd wager overwatering causes more bonsai deaths than any other single cause.
I will keep all those factors in mind as I watch over my trees heading into fall and winter. Its interesting that you mention this as in the books they never get that specific. Most like myself would assume that sphagnum of any kind would work.
Good point about the distinction not being made, It is an
extremely common mistake that has not so much to do with the people shopping, As the info they are going on.
[Who knew there were 2 kinds w/ essentially the same name but which bring entirely different properties to your soil mixture.]
IMO the confusion stems partially from the fact that the authors of these books are of differing international origin, [UK, Taiwan, Aus, Canada, USA, Japan, ect]
Not everybody has so many kinds of 'sphagnum peat moss' on the shelf, Meaning that in their local shop these two horticultural soil amendments may have two entirely distintive names and they are unaware of the need for making note of the difference. [Just OTTOMH on this, It does complicate things though...]
The sphagnum was sifted and the larger fibers used though when I did my repotting so hopefully that will be a saving grace. I did that based on my understanding that finer particles should not be used in repotting because they will reduce drainage drasticaly.
Absolutely correct wrt the fine particles. Excellent to hear you are Sifting your soil components.
That is doing your trees a huge favor right there.
While were on this maybe you should review for others what it is that we are looking for in repotting and what we are trying to accomplish during new root growth. I will contribute how I can but I would like to see what you as well as others have in there mind on the perspective of roots.
Is there anything speific you were wondering about as sometimes a general overview doesn't hit the mark if you know what I mean.
Do you mean wrt timing, or the purposes of repotting, or components of good soil, I will give it a shot.
Sort of a general overview including links will follow. [I have to see if I have {READ: Locate } Suitable pictures and move them to a suitable hosting site for posting.
Thanks for the interest

ynot
DISCLAIMER: I am an enthusiast, Not an expert....lol
NOTE: see the Subject
