Anytime the tree is dormant. Between January and mid April. Unless you
live in Australia.
Pruning orange trees should be confined to trimming extremely long
branches that become untidy or new branches that cross over others, they
do not require any special pruning to encourage flowers as these will be
produced naturally on new shoot tips and any wood old enough to bear
them. You should aim to keep branches fairly short so that they will
eventually become strong enough to carry the weight of half a dozen
fruit of 6 oz. You should also be aiming to keep the centre of the tree
quite open as this will allow plenty of light in to the tree.
Don't know much about Tangelo but I'd imagine it would be handled the same.
Here's a couple of helpful links. If you're on dialup it may take a bit
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.