I read on another website that you should trim the taproot once it's well-established to promote the growth of auxiliary roots.

A couple questions. First, is this a good idea? Second, if it is a good idea, what defines "well-established"?

Any insight would be helpful. I've got some babies about ready for transplanting to a larger pot and thought that might be a good time to do this.

If your planting it in the ground you do not want to trim the tap root. For container growth you are correct in trimming the tap root. I would make sure the trunk is at least pencil thick before trimming.

If the tree is planted into an Air Root Pruning container, the container would automatically trim the tap root by air desiccation. If the tap root is not trimmed it will constantly rotate around and around in the bottom of the container.

Millet
Anton van Leeuwenhoek
Founder of Polyembryony in citrus 1719

When planting container grown citrus in the ground and the tap root has made several circles at the bottom of the pot the tap root is cout off at the point it start to grow in circles.

Thanks for the feedback. They're nowhere near pencil thickness yet. They'll definitely be container grown, though.

Still going to transfer to larger containers - they're in coffee cups right now!