There is an article in Growing Bonsai about ash for bonsai, which I think means European ash. I have an ash tree that just decided to grow in a pot that had nothing else in it last year. Now it is about 1.5 meter tall and the bark is nice, but the leaves are huge. They are compound leaves, probably half a meter long, and the individual leaves are maybe 8-10 cm long. It just doesn't seem that it will agree to shrink the leaves enough to be a decent bonsai.

Is there a piece of technique I can use that will shrink them down to just a few cm?

I would say that all Ash have fairly large leaves. Defoliation and bud-clipping are used to reduce leaves. But I have mostly seen large specimens used for bonsai that look reasonable.

It's just sitting in a nursery container now. I guess I'll chop it down, then defoliate, etc., and see if it can (1) earn a spot in a real pot or (2) earn a spot in the trash can.

What is bud-clipping?

No experience with it, but removing the terminal buds of branches in winter so inner buds take over which are weaker.

On the subject of the tortoise and hare.....

I want to move not too fast, not too slow, but just right. I am going to chop the ash tree and defoliate it.

It is about a meter and half high, about 2 cm at the base, and all the leaves are at the top. It seems I want to cut about 3/4 off, which would get all the leaves, and it seems this may be too late in the year. If I chop now, there may not be anything to defoliate in June, so it seems I have two plans. Growing season here will extend into late September.

Plan A: chop now, defoliate in July or so.
Plan B: defoliate in June, chop in March.

Is there a plan C which is better? I asked Dr. Google and got nothing specific.