RoR Trident or strangler fig?

[SquatJar]

Two years ago I got a handful of maple seedlings from Neil, and among other things, I created 5 or so RoR tridents using his alfoil technique.

From memory this seedling had minimal roots, not even halfway down the rock so I left an opening at the top of the alfoil wrap and watered it by dribbling water down the hole for its first summer.

I filled the bottom 50mm of the pot with my usual perlite, diatomite and zeolite mix, then I filled the rest of the large pot with heavy sand to apply pressure to the alfoil. I used a few layers of shade cloth to try and keep the sand away from the coarse mix below. After the first summer I watered the pot/sand as usual for the next 18months, due to the large pot and sand mix it only required water maybe once a week during summer and not at all during winter. I was concerned this meant that the sand may have clogged the mix below quite quickly but during repotting today I found that was not the case.

The roots had grown well into the coarse substrate below, but when I unwrapped the rock I found roots all over it like I've not seen with my others. There is fine root everywhere, even growing 40mm or so upwards covering the top point. I'm not sure if this is a different type of rock that the roots love, or the sand on the outside meant that there was only oxygen available by diffusing through the rock. The roots at the bottom of the pot were just as healthy, no rotting, or bad smells.

I then had the luxury of choosing which roots to remove and which to keep, sorry there aren't any pics of this, my hands were filthy, and I was too focussed on the root removal and forgot.

Any straight roots were cut, I left more small roots than I've seen other people leave, my reasoning, right or wrong, is I like the look of roots melted and flowing over the rock as opposed to 5-10 individual, larger, round roots growing over the rock. The main concern is that they all merge and minimal rock is visible in the future. I left a few bare patches to try and avoid this. Only time will tell. If I did this again I wouldn't have planted the seedling so near the top and not in such a straight line. I may be able to fix this in the future by cutting hard and getting back buds or by grafting into the roots.

PXL_20210726_061547352.jpg

[shibui]

I've also found that soil acid dissolves alfoil so I replace foil each year. Trident roots love to get out and then grow fast which can spoil an otherwise great root arrangement.
I also get lots of new feeder roots all over the rocks. I guess wherever there is moisture and nutrients the tree will grow roots to take advantage.
Definitely leave some bare spots. You want people to recognize that it IS root over rock in 10 or 20 years, not just a fat trunk trident. You can always cut a few more roots if you realize they are taking over at some stage.

Good result from a first attempt at this technique. ROR looks easy but the more aspects that are combined the more things can go astray. Good ROR needs good rock, good roots, good placement on the rock and that's before we even start to develop trunk and branching so really good ones are not so common and not real easy to develop.

As you already mentioned we learn from each attempt and hopefully improve with each try.