Improving Young Root Over Rock Pines

Improving Young Root Over Rock Pines

Bonsai Design Japanese Black Pine Root Over Rock

Root over Rock is one of my favorite bonsai styles, and at any time I have at least a half-dozen young trees in training with auxiliary soil retention mechanisms in place to ensure that the roots make it into the main container so they can eventually be exposed to enhance the value of the composition.

After my first batch of pines, I got a bit more intentional with the stones and with the initial arrangement of roots, but even considering that work, there are improvements to make two or three years after the rock and stones were initially paired.

After three years sitting on top of this stone and having already exposed the roots and improved them once during a repotting last year, I am now looking more at the details of each root of this five-year-old black pine to ensure that they adhere to my vision, and that as they continue to mature that they will accomplish my goals.

There are some problems here: removing the black rope that I used to try to coax the roots tighter to the stone last winter, we can see that there are a few larger roots that are not conforming to the overall visual flow of the stone and the majority of the roots. Eliminating these roots will expose a bit more of the stone visually as well as harmonize the flow.

After carefully analyzing which other roots are coming from the same part of the trunk, making just a couple judicious cuts accomplishes a major improvement.

The movement and visibility of the stone are both much better. The scar left from the cut will heal pretty rapidly, and as the tree matures, the taper on the large root should smooth over nicely. I plan to leave the sacrifice branch in place for at least the remainder of 2020, perhaps longer.

The second tree I worked on is a four year old, and it has been on the stone only two full seasons. This stone was one of my favorites from my 2014 collecting trip; it has a large blocky feeling that I think can really be used to good advantage with the right tree design. I planted the tree on the back edge of the top of the stone, to the right of center, with the roots heading across the top of the stone and then down to the left.

After exposing the roots last winter I noted one of the roots had plunged vertically rather than trending to the left as I was hoping. Last winter I thought it was too small to attempt to move without killing it, so I waited a year.

Now the roots seem about the perfect size to excavate and move before they get too woody. The contrasting color and texture of the portion of the rock on the right is one of my favorite features, so I pulled the roots blocking the base of it and loosened them up. I had to cut a pencil-size root to loosen the left crossing root but there are plenty of small roots still attached for it to recover.

With the roots repositioned I pinned the small roots into the soil at the base. The change has allowed the aesthetic of the roots to more clearly harmonize with the textures and shapes in the stone. Now it’s time to wait, and bulk the trunk significantly more on this tree. I envision the tree to have a 3-4″ trunk diameter where it meets the stone, which will take a few years for sure!

Watch this video, showing this composition in three years later!


Root over rock can be done with many other species than just pines. Give it a try and let me know how you did. Leave a comment here and good luck growing!

Product notes: Looking for black pond baskets like what I use? You can find a lot of them on the internet, but most are made of low-quality plastic that will crumble after just a couple years in the sun. The basket used for the first example in this article was used to grow a tree 10 years ago, and I’m now re-using it and others for a new batch of trees. These baskets are produced by an English company and are called “Finofil” baskets. I do not recommend the blue colanders that you see in the second example as they crumble after about two or three years, as do similar ones of different colors. I do not recommend any of the baskets that are currently available on Amazon. I recently bought a batch of baskets from a seller off Ebay.

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