First Root Over Rock- Atropurpureum Maple

[BonsaiOnTheBrainTX]

Alright so I just got 3 good size limestone rocks that I purchased off of Etsy and I’d say they’re pretty perfect for root over rock. If anyone is trying to find good rocks I’d be happy to share a link to their store.
I have a bunch of young green and red Acer saplings, I went with the red on this one. It did not have as many roots as I would have liked but I think it will be enough, we’ll see. I was able to get the base of the roots into a good nook that I think it will grab onto. I was able to place 5 or 6 of the “longer’ roots into advantageous grooves and places that I think will look good. The areas on the rock that have the muck stuck to it is where I placed the roots. I made a muck with sifted akadama powder and finely shredded sphagnum moss which seemed to work well.
Initially I thought I was going to secure the roots into place with some wire…. It held the tree in place but not the roots, so I removed the wire and used grafting tape instead.
Once everything was in position I potted it up pretty deep in a 10in square pond basket and topped it off with a bit more sphagnum moss.
For the other 2 rocks I think one is going to be a green Japanese maple and the other I really want to do with a Brazilian Rain Tree. I have a young one that I think would be a good candidate, so I might do that tomorrow if I have time.
Here are the terrible pictures I did manage to get let me know what you think and any advice is appreciated!

 

[Shibui]

Nice start to ROR.
Well done removing the wire on the roots. My experience is the roots and trunk thicken as the tree grows and the wires bite into the roots leaving bad marks or even strangling the root completely.
Grafting tape will be more forgiving but may still leave some marks.
Another problem I've found is any new roots that start tend to grow out, away from the rock. Often those new roots get stronger than the ones draped on the rock. Sometimes the carefully placed roots will wither away because the new roots are strong and getting more feed and water.
I discovered aluminium foil is much more effective for developing ROR. No strangled roots, no marks, any new roots are forced to run down along the rock giving you extra roots right where you want them.
I gave up using muck for ROR. Had a number of poor results where the roots with muck all died. maybe my ham fisted approach but I find I get better results with foil wrap and no muck.

I prefer trident maples for ROR because the roots develop way quicker than JM but hopefully you get a good result with this eventually.

 

[BonsaiOnTheBrainTX]

Nice start to ROR.
Well done removing the wire on the roots. My experience is the roots and trunk thicken as the tree grows and the wires bite into the roots leaving bad marks or even strangling the root completely.
Grafting tape will be more forgiving but may still leave some marks.
Another problem I've found is any new roots that start tend to grow out, away from the rock. Often those new roots get stronger than the ones draped on the rock. Sometimes the carefully placed roots will wither away because the new roots are strong and getting more feed and water.
I discovered aluminium foil is much more effective for developing ROR. No strangled roots, no marks, any new roots are forced to run down along the rock giving you extra roots right where you want them.
I gave up using muck for ROR. Had a number of poor results where the roots with muck all died. maybe my ham fisted approach but I find I get better results with foil wrap and no muck.

I prefer trident maples for ROR because the roots develop way quicker than JM but hopefully you get a good result with this eventually.

Thanks for the response, I actually just watched a few videos where they used foil to hold the roots. But I don’t understand, do you use regular bonsai soil in between the foil and the rock?

Maybe I’ll check the roots next year and remove the tape, switch to foil at that time.

 

[Shibui]

But I don’t understand, do you use regular bonsai soil in between the foil and the rock?

There's no need for any soil between the rock and foil. As long as there's moisture the roots will grow just fine and within a few weeks they will grow out the bottom and into the surrounding soil.
Having a layer of soil would defeat the purpose because that will allow any new roots to grow away from the rock. No space between foil and rock means the roots must follow the rock contours very close which is the ideal for ROR bonsai. That's actually the biggest strength of foil. It can be moulded to fit close to almost any rock surface and get good results, even with odd shaped rocks.