Oak bonsai tree is not used in Japan historically, although it started in the 1950s in California. The big trunks and the tiny leaves of the oak make mature, fully grown trees elegant miniatures. The coastal live oak (Quercus agrifolia) is the easiest native oak to start with on the west coast.
How to Grow a Coast Live Oak Bonsai
- Choose from January to April a well-rooted sapling or baby tree about 6 to 2 feet in height. The leader should be soft enough to bend without cracking.
- Mix perlite and peat moss in a ratio of 1 to 1 to make a typical bonsai growing medium.
- Return the tree to a 1-gallon container with the usual bonsai growing medium.
- Prune robust shoots from the top of the tree with secateurs, thin pruning shears, or small scissors, leaving delicate shoots in place. This will help to shape and align the tree into a miniature shape, promoting dense growth at the bottom and thin growth at the top.
- Clip almost all the leaves of the tree with small scissors, leaving just a few leaves at the end of each branch and the chief to allow the tree to bud at the trunk.
- Cut aluminum wire one third longer than the branch or leader it is wrapped with. The wire diameter can be between 1/3 and half the trunk or branch thickness.
- Wrap the aluminum wire in 45-degree wraps around the branch and the leader, leaving 1/4" space between the rolls. Bend the tree to the correct form such that roots or new buds are at the outside of a curve, and do not break the bark.
- Set the tree periodically in the water and partial shade. The soil does not freeze in the winter but should stay moist.
- Fertilize the tree according to the instructions of the producer starting 1 month after it is repotted.
- Placed the branches in late autumn, after the tree reached its sleeping season. Cut the end-nodes out of a branch to facilitate the blossoming close to the trunk and to hold the lower branches with more and only the top branches with one or two.
Oak Bonsai Second Year Training
- Pull the bonsai tree gently out of its container by the trunk and reveal its roots shortly before starting to grow.
- Using secateurs or scissors, cut the root mass by one-third.
- Repot tree with the same pot in traditional bonsai medium or move it to a more decorative bonsai pot. Two-thirds the height of the tree should be the width of the decorative pot.
- Bend the branches or main leader closer to the final form you want and add wire to the new growth as necessary.
- Resume fertilizing one month after root pruning.
- Take the tree under 2 feet high and hold the ideal tree shape throughout the growing season.