Considering root-over-rock azalea forest but not sure (rules and techniques)

[Harunobu]

So the plan would be to use some of my seedlings and create a composition with rocks. The goal would be to make a forest while mimicking the way satsuki azaleas occur in nature.

So first is the rules thingy. I could potentially sow new seeds. But I have these seedlings sown on 14 October 2020. I see the rules state you can use seeds sown before 15 December (rule A), and that you may start germination on 15th of December (rule B)? These germinated well before the 15th of December. So can you use seeds that germinate before that date, yes or no?

The second 'hurdle', my idea is to put these seedlings on a type of rock or slab very early on. I noticed that azalea seedlings often grow their roots in the air, and that they harden off and become woody rather quickly. So the goal would be to set up the rocks, put some soil on top, have the roots grow down. And over the course of 6 or 8 years, lose more and more of the soil. So there will be no repotting. I have no experience with growing plants in or over rocks. All usual types of azalea potting mixes either compress (peat) or decompose (kanuma). And judging from the nature pictures, I need some rocks with pockets or reservoirs of soil in them for the roots to properly grow. Also, if I make a composition of rocks and they are not all attacked as one piece, then I can not really touch the soil at all and I even need the final bonsai pot or slab from early on. If the seedlings attach to several rocks, one cannot really move the rocks after one year, and rearrange them.

Another option would be to use a more traditional neagiri technique and grow long roots on the azalea seedlings:

Then extend the roots long the rock, guide the root tips to a soil pocket in(between) the rocks, and cover all the rocks with sphagnum moss for a year. Then finally expose the roots. I don't like this as much because to me the point of using seedlings is to let nature do the design. Put a bunch of seedlings on a rocky surface and let them struggle to survive. And in the end keep the strongest and best looking ones. And with time, the soil falls away, exposing more roots.

Not sure if that will work out, but seems worth trying something new, plus I have these seedlings to waste on it:


These were sowed 14th of October, they grow well, but I don't need them for my breeding programme.
If I can't use these but I can come up with a good plan, maybe with some advice and suggestions, I'l lconsider sowing some brand new seeds.

Main issue is to find some kind of rock to transplant these seedlings onto. I don't want to make a large piece. But I can't go to garden centers and see if I can find some ornamental value rocks, because they are all closed (covid19). I also don't know what type of mineral would be suitable. And I don't have power tools to create soil or drainage pockets. I think that ideally, the shapes of the rocks and the shapes of the final azalea seedling size would be somewhat in proportions.

Maybe someone has some ideas?

At this point maybe when spring comes and frost is over, I should just plant what is inside this tray in between two large rocks with peat and kanuma inbetween. And then just see what happens. Then since it is two rocks, I can move both at the same time to some future container (one rock in each hand).

If I can use these seedlings, I can post a seed to tray to germination follow up post.

 

[Forsoothe!]

You might consider using a lump of soft brown coal. Sort of a Dutch greenie thing! Back in the day when Europe used coal for power lignite was strip mined, so you should be able to do some research and find a closed mine somewhere, or if you're friends with a Welshman you could do some horse-trading for a lump. It's hard enough to retain a shape and soft enough to grind and carve pockets to please. It would be a several step plan where you need to make pockets for the finished root system, and extensions of those pockets, where the roots would begin, but would later be evacuated of media as you expose the upper root systems. You'd start by shaping the lower outside of the lump to your tastes, but leaving a couple inches extra height on the upper perimeter. Next, you mine your upper surface to your finished contour/shape in the center of the upper surface, except leaving a suitable retaining wall all the way around. You fill the whole upper surface with media of your choice and plant whatever strategically placed plants and over time undermine them until you get to the point where the media is only in pockets surrounded by land with roots helter skelter. As you remove media and chip the retaining wall down you can further complete the design of the upper surface adding strategically located new pockets for roots that need homes. Eventually, you have only pockets, land, and no retaining wall.

Soft brown coal is what leaches into the water table and creates an acidic wasteland, but you would be able to control that because you're a scientist! Leonardite is sold as a humic acid source and your lump of coal would slowly decay into plant food. Off you go, find a big lump and start carving!

 

[Kanorin]

Regarding the rule about starting seeds early: I made an amendment that basically says you can use seeds started up to 6 months early as long as you agree to submit your final contest photos early. If the seeds were started two months prior to December 15th 2020, then you would need to submit your final contest entry two months early (October 31st, 2029).

I love that I'm seeing people think about some non-traditional forests! Cool idea!

You are totally within the contest rules to try out some seedlings on rocks, some on coal, some on another substrate - and then go with whatever seems to be working after a few years.

 

[Kanorin]

I was watching one of Peter Warren's videos on satsuki Azalea repotting and he made a comment that planting azaleas on rocks or as root-over-rocks as very challenging because they really suffer when their roots get too hot. The comment made me think of your potential plans and how you might want to take some additional measures to keep the rock cool. Perhaps: Cover some of the rock surface with moss or keep the rock and roots mainly in the shade.

 

[Harunobu]

Yeah, it is a more challenging technique, in general. And I guess more challenging for azalea specifically as well. I was actually inspired a bit as well by those Korean youtube videos. Seems that Korean guy has a completely different style to satsuki bonsai than the Japanese. I saw some super stylistic neagari satsuki azalea.


The Korean channel has a lot where the roots are quite messy and sometimes artificial in an ugly way.

I think that once the exposed roots are hardened off and once it has enough roots further down, it should be ok. But the thing is, this is how satsuki azaleas grow in nature. So they can't be that bothered by it.

I am kinda thinking though that making the forest right now and keeping it that way is not going to work. I don't have a rock. Likely, the seedlings will struggle. And just putting them there and 'doing nothing' may not turn out so natural after all.
Instead thinking about growing several pieces apart and assembling them at a later point. Taking pictures now of the seedlings I want to use. I might transplant a few out and put them in a pillar of soil that I slowly expose. Then I can put them on rocks at a later stage. And as a final step, make come planting/composition way down the line.

I still will be on the lookout for some type of rock that has a nice gentle gradient downwards, with several peaks. I could make it an entirely level thing with soil initially, the peaks of the rock just above the surface. Then plant seedlings near those peaks. Then slowly let the soil wash away as the years pass.

 

[Kanorin]

Now you’ve got my wheels turning...Neagari azalea forest could be very neat.

 

[Harunobu]

Neagari-over-rock azalea forests from seeds; yup let's try something crazy. I have enough seedlings anyway.

 

[Forsoothe!]

Feather Rock, or pumice on the hoof is another material that can be shaped fairly easily. It is porous, so to speak, and absorbs a lot of water at the same time that it won't stay sodden, so that makes it a good prospect for a cool/cooling vessel for your neagari forest. If you have air tools and carbide bits it works well but you'll need to bathe after each session to remove the grit from every nook & cranny of your being. Always work upwind on a windy day and wear gloves, a hat, and eye protection. The roots will penetrate the surface making it hard to extract & repot, so repot a lot more often than typical for a given species.