Unwanted moss, or, Nomoto’s paradox

Covering bonsai soil with moss is a great technique for indoor exhibits. Covering your bonsai’s bark with moss is almost never a good idea. Moss weakens bark by keeping it moist. For trees on which bark denotes age – Japanese black pine comes to mind – moss can quickly ruin a tree’s appearance. In autumn, when dew begins to fall, moss grows quickly. It’s a good time to get the problem in check.

Moss on the trunk – what to do!

Tweezers are great for plucking unwanted moss, but tweezing can cause as much bark to flake off as moss. 50/50 mixtures of water and vinegar are great for killing moss on your trees, but it does little to remove the moss when it dies. How to proceed?

Several years ago I posed the question to Daisaku Nomoto, a very talented bonsai artist from Miyazaki who apprenticed with Kihachiro Kamiya. I remember the tenor of the exchange well – Nomoto was adamant: “You must remove the moss.”

“How?” I asked, “with tweezers?”

He replied, “But you can’t use tweezers or bark will fall off.”

“Spray vinegar?”

“Moss die, but you must remove the moss.”

“With tweezers?”

“But,” he said with a smile, “you can’t use tweezers.”

After several minutes of the like, Nomoto’s tautology lost its charm and I let the topic die. Vinegar and tweezers are clearly important weapons in the battle against unwanted moss, but as to their proper application, I’ll say no more.