I bought a Japanese maple seedling from a nursery. It’s quite tall but not mature. I’m thinking about cutting it down during the winter. What percentage of its height can I cut off?

I dont see any pictures. Generally, as long as you call it a seadling, dont cut back. Just let it grow.

Wes wrote:

I bought a Japanese maple seedling from a nursery. It’s quite tall but not mature. I’m thinking about cutting it down during the winter. What percentage of its height can I cut off?

You can cut back to a bit above the place where the first leaves were.
Question that is really important, should you cut it back.

Here’s a pic of my Japanese maple. It’s young but quite tall.

I would not cut this for a few years. Actually I would not grow it in a bonsai pot at all at this stage. What it needs right now is unlimited growth, then it is contra productive to grow in bonsai pot and cut back.

Tropfrog wrote:

I would not cut this for a few years. Actually I would not grow it in a bonsai pot at all at this stage. What it needs right now is unlimited growth, then it is contra productive to grow in bonsai pot and cut back.

That small bonsai pot is actually bigger than its original nursery container. The nursery pot was about the size of an Asian teacup.