Bonsai rock plantings imitate the awe-inspiring state of trees in harsh natural environments struggling to find nutrients and maintain health. I had never created batches of Juniper rock plantings before. I had previously put together a larger Juniper on a slab, and a small Juniper on a stone, but not using the same process; these never had a base, and the roots were growing in a small pocket of the stone, not down into a pot. I liked the idea of creating some compositions that were pushing the boundaries of what might be considered natural, into the "fantasy" realm. So in January 2020, I took apart a container full of rooted Kishu Juniper cuttings and used the cuttings to create rock plantings.
In preparation for the operation I took "lace rock" that I got from a stone yard in Santa Rosa, CA and first washed and then used a fabric spot gun (similar to a mini-pressure washer) to remove dirt. I took each clean stone and examined it for the angles that I liked the most and then cast small composite bases to allow the stones to be used at the best orientation. The entire process wasn't super difficult; it was inspired by Jan Culek's fall 2019 visit and by current Bonsai Society of San Francisco (BSSF) president Sam Tan asking me to help him with a much larger stone project needing a cast resin base.
I cast bases for about 25 different stones and then proceeded to create compositions to use the best features and angles of the stones.
To attach the trees to the rocks, I create a mixture of clay, akadama (Japanese bonsai soil), and sphagnum moss called muck. I used a small stainless steel screw to create a removable attachment point. In the past I've used a mixture of portland cement and super glue; but a warning if you try it - the resulting mixture is seemingly indestructible so you don't get any second chances. (Tip: wear disposable gloves!) Using the screws, I knew that they can be removed entirely if desired.
After observing these rock plantings for a full growing season I've learned a few things:
- Covering the muck with a good live green moss is a really good idea: it prevents the clay and muck from eroding when you water and also keeps the soil more moist.
- Watering, or lightly re-wetting just the muck mixture area on the upper parts of the stone will ensure the juniper roots can make it into the pot.
- The junipers that get their roots into the containers immediately start growing more quickly. If you see a tree sitting stagnant, try adding more muck and moss over the roots to encourage them to run downward.
Below is the back side of the planting in the main photo with this article. There are two juniper cuttings and both have started to grow nicely. I have not added muck or moss, but as a result I've had to scrape the top soil a couple times to remove built up clay that eroded. I will add moss once the rainy season starts.
If you're interested rock plantings, we have a Root-Over-Rock Japanese Black Pine bonsai kit available for purchase!