i have a small citrus that i grafted about two springs ago. i am currently training it to have one central trunk. there are some very low branches on this small tree. i figure once it gets larger it would be good to remove the lower branches. what is an ideal ground to branch height? i know the lower leaves helps develop the roots but eventually i will want more than 6 inches of trunk height.

I leave enough space to allow putting a cut 3 gallon pot filled with dirt .around the trunk for freeze protection.