How to grow round shape on top(maple trees)?

Question

I have a few speciments of Acer pseudoplatanus and Acer platanoides. I want to grow them, so they will have trunk without branches in bottom part and nice round "ball" at the top as that is often in urban landscape in cities.

I don't know when and how much should I trim them, so I ask you. Should I wait till the end of the growth period to trim new branches or do it now? I want tree to be about 2 meter high, a little more than ordinary human. I am located in continental Europe, so now we have growth period.

I added a photo how it looks like and another one what should it look like. The first image is one of my trees and the second image is the shape I want in the future.

Thank you!

Answer 1

I think the pictures show Acer platanoides "Globosum" which is described as

A grafted...tree displaying a formal broad, globe shaped head which needs no pruning

Most maples show strong apical dominance and are not suitable for pruning into a globe shape.

If you tried to prune your sapling by topping the central leader toy will get a lot of adventitious growth which will not have a good attachment to the trunk as the multiple stems grow.