How to go About Growing a Root-Over-Rock

[TerraAudeux]

I want to make a root-over-rock; specifically, one with a geode.
The rock isn't the issue; I have plenty of areas to search for the perfect geode.
The issue is growing it. I am quite new to the art of bonsai, and don't know how to make one.
What's the best way to go about it? Should I find a specific type of pot to grow the tree in first, to give them long roots?
Please advise.

 

[Wires_Guy_wires]

I use a tall pot. Planted a tree on a rock, tied the roots to the rock, and then filled the pot wil bonsai soil up until an inch or so above the rock.
Every year or or two years, I dig them up, rearrange and tie the roots back on.
I think someone on this forum had a great example thread with mugo pines. But I don't know his username anymore. If memory serves me right he has a profile picture wearing a white (fishing) hat.

 

[Paradox]

Works best if you start with a seedling / young tree whose roots can be shaped to the rock initially rather than a large tree whose roots cant be so easily bent to the shape of the rock.

 

[LittleDingus]

I want to make a root-over-rock; specifically, one with a geode.
The rock isn't the issue; I have plenty of areas to search for the perfect geode.
The issue is growing it. I am quite new to the art of bonsai, and don't know how to make one.
What's the best way to go about it? Should I find a specific type of pot to grow the tree in first, to give them long roots?
Please advise.

I recently started a thread where I'm trying to grow a root over rock with a geode

[Dingus] Willow Leaf Ficus (ficus nerifolia) #1 & #2

I'm going to track these two plantings together because they are planted on 2 halves of the same "rock" :) This first post will discuss planting #1. There will be a follow up post for planting #2. I've always loved rocks. Gemstones, semiprecious stones, tumbled stone, jaspers, granites...

www.bonsainut.com

Some things I considered that may be of interest to you:

Roots adhere to porous rock easier than non-porous rock. Depending on the nature of the geode, it may be in a porous lattice or it may be in a non-porous lattice. Take that into consideration. My geode is in a porous lattice...something I think the roots will eventually be able to adhere to. I am a little worried, however, the lattice is too fragile on my geode and the roots will just break it off. I don't think they can adhere to the quartz. I'm hoping that the ficus roots are fleshy enough to encompass the geode if they can't adhere to it.

Consider the size of the geode compared to the final size of the tree you would like. There are some limits on the size of the tree depending on the species you pick. Think about the proportions between finished tree and rock.

Consider the type of roots your tree makes. Some trees make better roots: more fleshy, naturally longer and more pliant, etc...I made the mistake on mine of trying to grow the tree out more before putting it on the rock. I ended up having to cut most of the roots off to get the tree on the rock Since I'm using a ficus, that's probably not such a big deal...we'll see. I have a maple on a rock that I started on the rock as a seed. After one year, it's looking like it's opting to grow roots down one side of the rock only...I may have been better of growing the maple out for a year or three then draping the roots over and tying them in place. Only time will tell. Point is, I took the exact wrong approach for each type of tree...I should have had the methods flipped based on how the different species grow roots.

I have a very particular vision in mind for my geode attempt. Can I achieve it? Probably not...but hopefully I can get reasonably close I changed my mind several times on the size of the rock and species of tree to use before I settled on what I did. Before you start, have a vision. Use it help you pick the right material...rock and tree...to meet that vision. Do try and understand if the tree and rock you pick _can_ result in that vision. I have a nice piece of petrified wood I'd love to grow a rainbow eucalyptus on. I have a very fanciful vision in my mind's eye. Realistically, the tree will never grow as I envision so attempting that project would be a fool's errand Think through what you know of how your tree grows and if it can produce what you envision.

...and good luck! Looking forward to see your progress!

 

[sorce]

@James W. Has a white fishing hat.

Welcome to Crazy!

Sorce

 

[Shibui]

Much will depend on the species of tree to be used.
As already mentioned roots will need to be flexible to wrap closely to the rock to look good. Some tree roots stay flexible for several years while others get hard very quickly. You also need a number of roots to wrap the rock so no point starting a seedling in a deep pot. Seedlings usually have one strong root. First root prune to stimulate a number of new roots then grow in a deeper pot for a year to get longer roots that can be wrapped.
If you try my foil method the roots don't actually need to be long enough to reach the bottom of the rock for success. Here are some of the Shibui Bonsai blog posts on root over rock https://shibuibonsai.com.au/?s=root+over+rock&submit=Search

Not every tree will fit a rock, even when grown for long roots. My advice is always start with several rocks and a number of trees to get the best chances of a successful match. Things can still go wrong during growing so make a number of attempts to maximize chances of a better root/rock/trunk/branch configuration in the end.

 

[James W.]

I use a tall pot. Planted a tree on a rock, tied the roots to the rock, and then filled the pot wil bonsai soil up until an inch or so above the rock.
Every year or or two years, I dig them up, rearrange and tie the roots back on.
I think someone on this forum had a great example thread with mugo pines. But I don't know his username anymore. If memory serves me right he has a profile picture wearing a white (fishing) hat.

mugo seedlings Doesn't really show the process very well. A search will find discussions with more better explanations..
Everything said here so far is spot on. I like to leave more room for dirt than @Shibui does with his foil so I use cut up pots to construct a barrier to keep the roots close to the rock as they grow.