Rock plantings are amongst the most dramatic bonsai, especially when extraordinary rocks are available. Thin flat rock slabs make exciting containers for group arrangements. Plants grown root-over-rock-into-pot have a very strong stable appearance. Landscapes can utilize a number of rocks. But perhaps the most dramatic rock planting utilizes a vertical rock to depict a cliff!
In these arrangements, the Japanese attach securing wires at several places in various ways. A small hole is sometimes drilled. A piece of "split-shot" fishing lead is placed over the center of the wire, inserted into the hole, and with a nail or punch, the lead is flattened to wedge inside the hole. Or tie around a nub in the rock. Or simply glue a wire loop with any of the high-tech glues the are becoming available.
These techniques all work. It is very desirable to extend the roots all the way down into the pot so the roots can utilize the larger amount of growing media in the pot. It is possible to change the pot media from time to time to assure strong growth and the rock planting will not become stunted as when you simply plant a tree in a hole in the rock.
The Wire-Ladder technique was developed primarily for vertical or cliff plantings. In theory, with this technique, it should be possible to plant onto the side of a smooth perfectly vertical surface. It would simply require figuring out how to attach the wire-ladder!
||1. The vertical rock
2. Cement base to stabilize the vertical rock
3. Hole screen secured by a bent wire.
4. The pot
5. Coarse drainage layer
6. 1/4" thick layer of spaghnum moss to easily distribute water throughout the built out section. Note that there is a large amount between the tree and the vertical rock. In watering, gently aim water above the tree to hit the rock and this will send water down to water from the inside. Water several times to assure enough water saturates the media.
7. The "Wire-Ladder"
8. Tie the larger roots to the wire-ladder with paper-covered iron wire that will rust off or string that will rot off.
9. Smaller roots will find their way into the media behind the wire-ladder and down into the pot.
10. When all roots are attached, cover with a thin layer of spaghnum moss and Fuku-Bonsai's "Organic Bonding Compound" and attach growing green moss sheets to finish.
11. Complete potting by adding body mix, top dressing and surface moss.
FUKU-BONSAI'S "ORGANIC BONDING COMPOUND"
In Japan, a highly organic muck called "KETO-TSUCHI" is used for the same purpose. When I tried to find out what it was, I was told it is the very fine muck that is 3' under rice fields that have been cultivated for over 300 years. I don't know if that's true or not, but know that it dries rock hard and once dried out, it's almost impossible to get water into it!
In the 1990 International Bonsai Congress at the Sheraton-Waikiki that was co-sponsored by Bonsai Clubs International and the Hawaii Bonsai Association, Fuku-Bonsai provided the rock, plants, and container used by Japan bonsai master Shinji Ogasawara in the creation named "Takamiyama." He positioned the trees utilizing numerous wires and only Keto-Tsuchi. After the convention, the planting was brought back to Fuku-Bonsai where it was replanted based upon the original design and plant placements but with the wire-ladder technique. It continues to thrive.
As a certified export nursery Fuku-Bonsai cannot use any dirt and we developed the following formula to replace "keto-tsuchi:"
"Stir constantly while cooking a mixture of 1 part cornstarch with 3 parts of water until the "pudding" is clear and thick. Cool. Mix equal parts (by volume) of fine granular soil, damp long-strand spaghnum moss, and the starch "pudding." Use more pudding if you want a softer stickier muck and more media for a stiffer muck.
AN ALTERNATIVE TO DISPLAY FINISHING: In stead of the green surface moss, wrap the rock-planted sections with aluminum foil with a funnel-shaped top to catch water and direct it to the roots. The foil also serves as a mulch to keep the roots from drying. This alternative makes after care easier and moss can be planted later after the planting is well established. When this technique is used with ficus, Brassaia, or Dwarf Schefflera, the roots end up being fully and dramatically exposed.