Repotting Trick: The Plumb Bob

A familiar dance at repotting time is excitedly getting a tree out of the pot, carefully working the roots, locking it all in with wire, adding media, and standing back only to realize the trunk is leaning 10 degrees off. You swat your forehead. Or, you are being careful, and have stood back, made adjustments, and then the final two twists of wire nudge the trunk 3 degrees. It looks close but something is…off. You swat your forehead.

This gut-swoop is most common at a yamadori’s first potting, when huge inclination changes—sometimes 90 or more degrees—make us yearn for an alarm bell that will wake us from the close in work to stand back and see the big picture.

The carpenter’s friend, a plumb bob, denies the need to revisit the photos you took when styling the tree. You can get the orientation right with a far more accurate tool. 

Plumb Bob—a simple device for finding the correct repotting inclination

A few simple elements construct a plumb bob for a bonsai: a fishing weight, string, and a thick wire.

By altering the inclination of the tree the lead weight swings, and the ‘correct’ inclination (decided at the time of styling or restyling) is when it is directly over the wire tip.

After attaching it there’s only one rule: don’t bump the wire. If you can find a place on the tree to mark with a dot, where the bob hangs, then you can forgo the wire. But it’s not always possible to find such a spot and a wire wrapped at a convenient spot is a good second choice. 

A useful tool then, the plumb bob. It won’t tell you where the front is, but does help with another big decision, inclination.

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  1. Frank Hovenden says:

    It seems like a simple trick, that I had never thought of before. Thanks

  2. Mitch Fennell says:

    Simple, elegant, and practical. Thanks for the tip.

    • crataegus says:

      Wonderful, glad to hear. Though I can’t take credit for it, many who work with yamadori in particular use this trick, or thought it comes in handy during any major restyling.

  3. fratermagno says:

    I’ve loved the trick Michael.
    Thanks a lot

  4. Wawaset Warrior says:

    It probably goes without saying but I’m thinking that the table that the pot is resting on needs to be perfectly level.

  5. Dave Leppo says:

    I love it. As a mechanical designer by day, I tend to do better with mechanical bonsai techniques than, say, horticultural issues. Like using screws for anchoring or bending. A plumb bob is actually even more accurate than a spirit level (with the bubble in a tube), but most trees don’t have a surface for a level, anyway. There is a fishing weight called a Sand Spike that has a pointy tip, though these may run in sizes larger than what we want here.

    • crataegus says:

      I’ve seen folks using what seems like the Sand Spike. I only saw photos so not sure of the size. Cool point that the plumb bob is more accurate than the spirit level!

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