Coast Live Oak, #2336 A&B
Coast live oak—Quercus agrifolia. Armando (Hayward), Aug 2023, 2X $25/ea.
This is an iconic coastal species along the Pacific coastline of North America. As one of the most interesting oak species in the world to be used as bonsai, this broadleaf evergreen never fully defoliates.
Pruned upward shoots at the base, crotch buds/branches.
Wired branches laterally, down-up and let branches grow.
BSSF calendar recommends that evergreen oaks to cut leaves in half or repot in September. Heavy pruning & wiring in November.
Jan 2024–repot out of poorly draining, mud brick. Akadama: Lava: Pumice at 50:25:25, and a hint of basalt fines on top.
Dual trunk planted at a greater angle. Very fine and few roots, possibly too water-logged.
Jan 2024 SBBK JT on seasonal Oak maintenance:
JT suggested that the long straight trunk could be chopped to a node/bud and grown out as desired.
I am unsure of how healthy the roots are now given the poor health of the soil/roots—prior to recent repot.
He developed oaks in a large pond basket with aggregate soil.
Coast live oak care
Because coast live oak grows in the Mediterranean climate in California, it loves heat and can grow in incredibly hot, dry conditions.
When kept in a deeper container that has a reservoir of water, full sun exposure will create tight inner nodes, small leaves, and a strong tree that is very responsive to bonsai operations.
When fertilizing coast live oak bonsai, avoid high nitrogen fertilizers. Opt instead for a solid fertilizer once per month or a liquid fertilizer once per week during the growing season.
The best time for structural pruning and branching of coast live oak bonsai is in the spring, prior to growth. You can come back to pruning in midsummer after the tree has had time to produce a strong flush of growth and has built up a lot of energy.
Coast live oak can produce a second flush of growth toward the end of July to mid-August, but you want to avoid any heavy reduction of foliar mass or branching as you get closer to fall.
Without the foliar mass or the leaf to create the resources it needs, the tree cannot grow strong for the following year.
Refinement pruning and partial defoliation require you to prune back the elongated shoots to two active present buds and reduce the remaining leaf surface by two-thirds. This will stimulate ramification.When repotting coast live oak, you never want to bare root or heavily reduce the sheen at any one time. The focus should remain on ensuring the health of the soil and the sheen. Sheen base trees thrive in deeper containers.
Coast live oak bonsai can have a variety of soil circumstances when repotting, depending on how much control you have over your watering. You may use a solid akadama soil or a 3-1-1 akadama, pumice, and lava mix as long as you can customize your watering schedule.
Bonsai Mirai
Collectors recommend that most of the foliage be removed after collecting to manage water loss. It back buds extremely well. The tree makes use of extensive, horizontal roots near the surface, which makes it the least drought tolerant of California oaks. It is, however, quite fire resistant. It is, however, highly susceptible to sudden oak death (Phytophthora).
Phytophthora is a soil dwelling pathogen related to algae, and found extensively in California’s fog belt. Other plants host the pathogen in foliage, but oaks get infected trunks that quickly lead to the tree’s death. You can read more about it. Treatment of forest trees is problematic, but fortunately for us preventative treatments are possible for pot grown trees. A product called Agri-Fos is available
East Bay Bonsai Society
The growing medium of any oak species should be about 40 percent organic material and 60 percent aggregate or nonorganic substrate. As oaks native to North America grow in all types of local environments, they are quite adaptable to common bonsai growing media.
Oak bonsai plants not only tolerate full sun better than many other bonsai plants, they also need a good bit of direct, full sun, preferably in the form of morning sun that is not so hot and drying during the summer. During hot afternoon hours, oak bonsai need to have filtered sun to full shade.
Bonsai Tree Gardener
When oaks are wired be careful to remove the wire before it bites into the bark. Wire marks will be visible for a very long time. Guy wires can be a good choice instead.
Bonsai Empire
Examples for inspiration
