Bonsai repoting: ume

Wednesday, February 24, 2010

Bonsai repoting: ume

Several years passed – no flowers. I’d already carved away the lower 3-4 inches of the trunk and begun developing the nebari. I carved the trunk and helped new branches ramify. But no blooms. I’ll admit I am no fan of double pink, but the point of ume is the contrast between new flowers and old trunk. So I started grafting.
Another 5 years passed. The tree looked great with white blossoms – the fragrance was unforgettable – and I would had fun learning how to care the variety. But ume don’t bud back well, and the grafting became a regular affair. Then, out of nowhere, a few dark buds appeared from some of the original branches. Before long, I saw the first few double pink flowers. Which confirmed my decision to graft.
This year I am mid-re-grafting the entire tree. I let the branches grow past where I can safely cut back so I am essentially starting from scratch. Here is the tree a few weeks ago with the last few white and pink blossoms.
Ume – early February

White flowers
Double pink flowers
Last year I had good luck with my grafts – over half took and I ended up with around 7 new shoots. Another dozen or so grafts and I’ll be back in business.
Scion – one year after grafting
Another one-year old scion
Typically I grafted in years when I didn’t repot. This is supposed to maintain the vigor of the tree and help push energy to the scions. I hadn’t repotted the tree in a few years – not a problem because the pot was large and the drainage good – but I remembered doing things differently the first time I grafted the tree.
I looked through old photographs and found that when I grafted I cut the branches back heavily and re-potted at the same time. I thought I’d try the same this year. Here’s a shot from below half-way through cleaning the bottom of the root-ball. Not standard practice, but clearly demonstrative of the amount of roots removed.
Half-way through the rootball
I removed all roots up to the base of the trunk. I knew the base of the tree was flat because I hand carved through three inches of wood ten years ago and still remember the blisters. The work was far easier this time. To further encourage outward growing roots, I removed all growth from the base of the trunk.
Removing downward-growing roots
Bottom of the rootball prepared
I cleaned the remainder of the rootball and realized the nebari was developing well. When I first changed the level of the nebari, only three or four large roots emerged from the base of the trunk, the rest emerged a couple of inches higher. Now fine roots circle the trunk. Not necessarily expected of ume bonsai – trees on which deadwood is far more important than roots – but not undesirable either.
Rootball trimmed
As several years of residue from organic fertilizer displaced most of the bonsai soil left in the roots, I decided to wash the rootball to improve the drainage.
Rootball after washing away excess soil and fertilizer
I set to grafting right after repotting. Here’s a brief step-by step:
1. Insert scion in branch
2. Tie scion in place with grafting tape
3. Secure grafting bag around scion
Graft completed – note condensation from moist sphagnum moss in grafting bag
Grafting and cutback really cleaned up the tree. Here’s how it ended up.
Ume after grafting and repotting
I will have a good idea of which scions will make it around Fall. Some usually brown out immediately, others offer a green tease and then flame out in summer. If the grafts make it to Fall, I can usually count on their success. The goal is to get enough in place to begin thinking about showing the tree at a future BIB exhibit. When that time comes, I have just the pot in mind – a yellow oval I picked up in Japan last year – great motivation for me to keep up the work.


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