Defoliation
Defoliation is a practice to develop a tree with smaller features, like shorter internodes and smaller leaves.
Sei Boko Bonsai Kai (May 2023–Val M.)
Building out ramification after primary & secondary branches are developed.
If you want to develop lower branches, put the brakes on the top (apical dominance), then balance out.
Can trim top and leave lower branches to get a boost of energy.
Bushes are not apical dominant (azealia) and this does not work. Top/Bottom
Defoliation and cut-back
Reduce leaf size
Maintain ramification—must cut back to encourage ramification
Weakens the area of defoliation
Makes it easier to wire
Do when bushy, healthy and hardened off. Runners.
To reduce internodes, pinch apical leaf/shoot at the right time to prevent the prior internode from getting too long. Timing.
Can leave some leaf besides new buds to take some of the energy and dwarf the new growth.
Some can take full defoliation (multi flush), or needing partial defoliation (single flush)
Some can tolerate full defoliation, see how it grows back—if not much regrowth then give it a rest
Junipers
Junipers cannot fully denude—roll foliage to shake off older needles and then younger needles will flourish.
Tridents
Tridents easy to defoliate leaf but leave pedial (the new bud is near the base of the pedial. Due to oxin (hormone) it will want to grow. Cut back on the branch or trunk to encourage the next bud to grow out. Don’t get too close to the bud to cause damage.
Focus on the buds not the pedial
Cut back on hardened branches—not new tender growth. Let that grow out to generate energy prior to cut back.
Thinning out branches (to create inner light) strengthens remaining branches—so can select which branches you like
After a full defoliation they put the tree in shade or care for delicate condition for a week or so (if above 70F)
Pines
Japanese Black Pines: candles, cutting back wil give off more growth.
Japanese Black Pine—considered multi-flush, but check your tree.
Japanese White Pine—single flush, trim bud/candle in half only
Boxwoods
thin out, leave newer growth, make it less dense. Can remove older, inner leaves.
Removing inner leaves can help define the ramification
Boxwoods buds out inner branches easily
Bonsai empire: defoliation
For most Bonsai tree-species June is the best month to defoliate, leaving enough time to grow new leaves and prepare for the winter season. The exact moment depends on the tree; defoliate after the new spring-growth has hardened off.
Japanese Maple
If the tree looks healthy, “the standard practice once the new growth hardens off is:
Cut long extensions back to one pair of leaves unless you need to extend the tree in that area.
Cut off one leaf from each pair leaving a short bit of the petiole (stem)
Cut the fingers off of the other leaf.
This should produce a another flush of growth, primarily from the base of the terminal leaves (on cut off the other trimmed), but may also drive back budding.” [Bonsai Mirai forum]