Transplanting a 1,500 Year Old California Juniper Bonsai

Transplanting a 1,500 Year Old California Juniper Bonsai 

By George Haas 

On December 31, 2023, the task of transplanting a 1,500 plus year old California juniper bonsai was undertaken by Peter Tea, a notable bonsai professional, at the Golden State Bonsai Federation’s Bonsai Garden at Lake Merritt, in Oakland, California. 

The California juniper was collected in the 1990’s from the Sand Canyon in the high Mojave Desert located in southern California. The tree was donated by Oliver Kilroy. 

Yamadori” means in Japanese “collected from the wild”. The tree’s first transplanting was soon after being dug up and placed in a large, growing box for three to five years. This period would allow the tree to recover and to grow feeder roots radiating from the trunk, just below the soil surface. When the tree is healthy, foliage is bushy and branch runners appear, can it be fitted to an unglazed, clay bonsai pot. In this case, a very large, rectangle pot. 

All bonsais require re-potting from time to time. A general rule for a large bonsai tree would be five to seven years due to the following factors: 

  • Age of the tree 
  • Size of the tree and pot 
  • Breakdown of the soil or compacted soil 
  • Root growth or root bound 
  • Water flow decreases 

The last time this California juniper was re-potted was more than 20 years ago. 

Due to the age of the tree and length of time since its last transplanting, Peter was requested to undertake the task. Peter was assisted by his apprentice Eli Iristree, long time client Max Vally and garden volunteer Michal Tiede. 

The tree and its root ball had to be gently removed from its current pot. It took everyone’s effort to lift the tree out of the pot. The tree was removed to the workshop area where work would begin on the root ball. Root pruning is necessary to clean up dead roots and shape the root ball to fit into its new pot. An unglazed, oval brown in color clay pot was chosen. The new pot is smaller in size and so careful shaping of the root ball was required. 

Fitting the tree to its new pot requires a trained eye. Peter would look for equal distance and balance, making sure the right angle and/or levelness were obtained in settling the root ball into the pot. Next, comes the wire tie down of the root ball and tree. This step is required of all bonsai trees so that there is no movement to disturb the growth of fine roots. Movement can damage the fine roots causing root rot. 

New bonsai soil mix is then added to the re-potted tree. Peter uses a measured mixture of medium size pumice and Akadama pre-mix from Japan. The pre-mix is part Akadama, pumice and lava rock. Here they work to fill all the air pockets that surround the root ball. They moved the bonsai tree back to its bench to complete the work. Only when satisfied that no air pockets remain, Peter will water thoroughly. 

Water is important to a healthy bonsai tree. Watering a newly transplanted bonsai tree is critical. Water must soak into the freshly added soil mix and drench the root ball and roots. Peter takes pride in using the water hose to water down the newly completed transplanting of this old, California juniper. The tree will be monitored for weeks to ensure nothing went wrong. From all appearances, the California juniper looks great in its new pot.

Front view, before repotting

Front view, after repotting

2 thoughts on “Transplanting a 1,500 Year Old California Juniper Bonsai”

    1. That’s a great question, Andy
      It took several bags of pre-mixed Aoki Akadama and horticultural pumice mixed at one to one parts to complete the repotting of this California juniper.

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