Root over rock

Rod

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I found a nice lava rock. I was wondering if I can plant a trident maple on it. It’s very porous and would have to clean rock out as I lifted it out of the soil Anyone have experience with this?
 

Shibui

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I have a trident on lava. Some great shapes so definitely useful for ROR.
A couple of things to consider:
Use young trees with flexible roots to start ROR. Nothing worse than roots that do not flow over the rock clasping it close like they grew there. Older trees have stiff roots that will be difficult to mould to the surface.
Try ROR foil technique rather than planting in soil or muck. No need to clean the rock when roots are grown.
Also no need to progressively reduce soil height. Provided root tips are in the soil below you can lift ROR to full height in one go. Roots will still thicken in proportion to growth above. Not dependant on being in or out of soil.
If you insist on using muck or soil most will wash away as you raise the tree year by year. Any remaining soil can be washed away with jets of water or toothbrush and water.

All bonsai plantings with rock are subject to extra moisture losses as rock absorbs water from the soil and evaporates it to air. Absorbent rocks will take a little more but every rock planting -ROR, slabs, Saikei, etc will require more water than equivalent bonsai without rocks.
 

Rod

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I have a trident on lava. Some great shapes so definitely useful for ROR.
A couple of things to consider:
Use young trees with flexible roots to start ROR. Nothing worse than roots that do not flow over the rock clasping it close like they grew there. Older trees have stiff roots that will be difficult to mould to the surface.
Try ROR foil technique rather than planting in soil or muck. No need to clean the rock when roots are grown.
Also no need to progressively reduce soil height. Provided root tips are in the soil below you can lift ROR to full height in one go. Roots will still thicken in proportion to growth above. Not dependant on being in or out of soil.
If you insist on using muck or soil most will wash away as you raise the tree year by year. Any remaining soil can be washed away with jets of water or toothbrush and water.

All bonsai plantings with rock are subject to extra moisture losses as rock absorbs water from the soil and evaporates it to air. Absorbent rocks will take a little more but every rock planting -ROR, slabs, Saikei, etc will require more water than equivalent bonsai without rocks.
We’re do I find information about the foil technique? Thanks great information I wouldn’t have thought the rock would pull water, I’d thought it would help hold water especially lava with holes in it. I will keep it in mind now.
 

Paradox

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Just want to second Shibui's recommendation on young plants.
A small seedling that you can grow the roots onto the rock will be much more convincing than an older tree with the roots strapped down to the rock in hopes they conform.
They usually dont and it looks just like what it is, a tree that had its roots tied down to the rock
 
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Rod

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Just want to second Shibui's recommendation on young plants.
A small seedling that you can grow the roots onto the rock will be much more convincing than an older tree with the roots strapped down to the rock in hopes they conform.
They usually dont and it looks just like what it is, a tree that had its roots tied down to the rock
I’ve got some seedlings I remove the tap root and plant it over the rock and tie it in place? This is my first attempt at ror
 

Rod

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I have a trident on lava. Some great shapes so definitely useful for ROR.
A couple of things to consider:
Use young trees with flexible roots to start ROR. Nothing worse than roots that do not flow over the rock clasping it close like they grew there. Older trees have stiff roots that will be difficult to mould to the surface.
Try ROR foil technique rather than planting in soil or muck. No need to clean the rock when roots are grown.
Also no need to progressively reduce soil height. Provided root tips are in the soil below you can lift ROR to full height in one go. Roots will still thicken in proportion to growth above. Not dependant on being in or out of soil.
If you insist on using muck or soil most will wash away as you raise the tree year by year. Any remaining soil can be washed away with jets of water or toothbrush and water.

All bonsai plantings with rock are subject to extra moisture losses as rock absorbs water from the soil and evaporates it to air. Absorbent rocks will take a little more but every rock planting -ROR, slabs, Saikei, etc will require more water than equivalent bonsai without rocks.
I have some seedlings planted through a Cd would I want to wait till they start to grow roots above the cd and use those roots? To possibly get a more radial nabari They are trident maples
 

penumbra

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The advice given here is excellent and useful.
Personally, I find most lava rock boring, but this is on me. I used a lot of it 30-50 years ago. I don't feel lava rock has much 'personality', but it is very easy to use. I have a number of pieces kicking around the garden, perhaps I should give it a second look.
I am very glad to see this post as I am considering starting some ror this year. Thanks for all the good advice.
 

Paradox

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I’ve got some seedlings I remove the tap root and plant it over the rock and tie it in place? This is my first attempt at ror

The best thing to use is something like grafting tape (ps its not sticky, its basicall a strip of plastic ribbon) as it shouldn't cut the roots.
String or wire could.

Then you bury the rock in the pot and let the roots grow around it. You slowly expose the roots a bit every year until the rock is exposed, the roots around it lignified and roots have extended below the rock into that soil. Those bottom roots are the ones that will support the tree so its very important to let the tree grow plenty of those as yiu expose the rock
 

Rod

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I forgot to take pictures but I used grafting tape and tin foil. Now I wait to see how it works.
 

Lorax7

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I found a nice lava rock. I was wondering if I can plant a trident maple on it. It’s very porous and would have to clean rock out as I lifted it out of the soil Anyone have experience with this?
Unless this lava rock is a smooth, relatively non-porous kind (pahoehoe, not a’a), I would pick a different species of tree to plant on it. A trident maple has to stay outdoors all winter. Under those conditions, porous lava is going to be weathered by water getting in the little holes and expanding when it freezes, creating little cracks and wearing away at the rock. If you plant a tropical tree instead, it’ll be indoors over the winter, so the rock won’t get crumbly.
 

Rod

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Unless this lava rock is a smooth, relatively non-porous kind (pahoehoe, not a’a), I would pick a different species of tree to plant on it. A trident maple has to stay outdoors all winter. Under those conditions, porous lava is going to be weathered by water getting in the little holes and expanding when it freezes, creating little cracks and wearing away at the rock. If you plant a tropical tree instead, it’ll be indoors over the winter, so the rock won’t get crumbly.
The rock has been out side in the weather for several years. I keep my tridents in my garage or greenhouse. At this point I’m not worried about freezing and thawing on the rock.
 

Shibui

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We’re do I find information about the foil technique?
Check Shibui Bonsai blog - https://shibuibonsai.com.au/?p=2631
That page will start you at the end of the process but follow the 2 links for previous stages.
Grafting tape, string, plastic wrap, etc is fine for rounder rocks but where there are hollows the tape doesn't hold the roots in close. Foil has the advantage of moulding to follow the contours of the rock so holds ALL roots close. If you apply it properly there's also no gaps where roots can escape as happens with string binding. All roots are forced to grow down inside the foil following the contours of the rock and emerge at the base.
Pressure of soil against the outside of the foil should hold everything tight for a year while those roots grow. I usually find masses of new roots inside the foil when I open them up a year later.
Good luck with this attempt.

As some encouragement here's a photo of my trident on volcanic rock.
CH220569.JPG
 

Rod

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Check Shibui Bonsai blog - https://shibuibonsai.com.au/?p=2631
That page will start you at the end of the process but follow the 2 links for previous stages.
Grafting tape, string, plastic wrap, etc is fine for rounder rocks but where there are hollows the tape doesn't hold the roots in close. Foil has the advantage of moulding to follow the contours of the rock so holds ALL roots close. If you apply it properly there's also no gaps where roots can escape as happens with string binding. All roots are forced to grow down inside the foil following the contours of the rock and emerge at the base.
Pressure of soil against the outside of the foil should hold everything tight for a year while those roots grow. I usually find masses of new roots inside the foil when I open them up a year later.
Good luck with this attempt.

As some encouragement here's a photo of my trident on volcanic rock.
View attachment 489300
That looks great I’m hoping for something similar. Thanks
 

Rod

Mame
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Check Shibui Bonsai blog - https://shibuibonsai.com.au/?p=2631
That page will start you at the end of the process but follow the 2 links for previous stages.
Grafting tape, string, plastic wrap, etc is fine for rounder rocks but where there are hollows the tape doesn't hold the roots in close. Foil has the advantage of moulding to follow the contours of the rock so holds ALL roots close. If you apply it properly there's also no gaps where roots can escape as happens with string binding. All roots are forced to grow down inside the foil following the contours of the rock and emerge at the base.
Pressure of soil against the outside of the foil should hold everything tight for a year while those roots grow. I usually find masses of new roots inside the foil when I open them up a year later.
Good luck with this attempt.

As some encouragement here's a photo of my trident on volcanic rock.
View attachment 489300
Great articles perfect information thanks for sharing this. This is why I like bonsai nut. All of you sharing and helping. Thanks I’ll let you know how it goes.
 
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