Inherited 10 trees of different varieties given to me without root-balls (5-6ft tall). 7 of the trees are thriving but three lost all their leaves. Should I cut back and wait till spring. I have continued to water. Also, one of the trees has two main stems, both seem to have root stock thorns on them. Any advice is helpful. I have summer pruned and fertilized all the trees. The ISD tag on them says 08/11/11
These articles have information on care and pruning of citrus.
I'm not sure of your growing zone, you may want to check with your County Extension Office to see if the varieties you are growing our proper for your zone.