This repotting season I’m planning on trying to add a mossy layer to my trees using Ryan’s topdressing technique with a mix of sphagnum and locally sourced mosses.
All of the information I can find says to add the topdressing mix to your trees right after a repot. Why wouldn’t I be able to add the same mix to my established trees that I haven’t repotted this year? Is it something to do with the root system not being adapted to a top dressing? Since I’ll have a bunch of the stuff mixed up, it would be convenient to just add it to most of my trees and not just the few repots.
This is how I understand it. Doing it right after repotting before you water the tree helps everything mesh together. If you surface clean your trees you want to top dress, but aren’t repotting it will help the top dressing adhere and establish.
you can do it even if its not freshly repotted, doing a surface cleaning if there is lots of broken down particles while the tree is on the drier side, then replenish top soil and top dress. If you dont need to clean the sirface you still can do it but they key is watering it in, so do it just when the tree needs watering and water it in
I have come across this a few times watching the Q&As! It has something to do with the way that the water column works within the confined growing space. I believe adding the moss now, ends up reducing the amount of oxygen within the container which we all know what goes wrong when O2 and water is out of balance. I have seen Ryan mention that if you lose water percolation and need to do some soil maintenance you can then add a top dressing after. Im not sure how to suggest moving forward, aside from maybe running a experiment? Try picking 2 trees you might not be as attached to and use them as the test subjects! But just an FYI I did this last season out of the same desire you had… not a single tree or container has any of the moss I applied. However, this fall I had moss spores germinate from the spores introduced last year, its super slight but it is a natural topdressing!
I am curious to see where you end up taking this!
As long as you sifting the moss particle size to accommodate the soil particle size…no moss smaller than your smallest particle size 1/16th for example it shouldn’t impact the oxygen in the water column. It’s when the “fines” or smaller particle sizes get in between the gaps in your substrate it reduces oxygen. This is my understanding and I even top dress my wife’s house plants these days… everything but succulents and cactus get dressed