Thank you for asking about pruning tangerine trees. Your question was:
"Do I need to prune or cut back my tangerine tree now, or ever"?
Pruning tangerine trees - Allow me first to congratulate you on a great looking tree! No doubt it gets treated very well, so well done. As for your question - it has two answers, and you can chose the one that suits you best - both are fine.
O.K then, let's prune!
Answer #1 - Pruning your tree right now is not a must. Your tangerine looks to be in good shape. The leaves are solid green and fresh and I can even see some fruits on it. So doing nothing at this moment is fine.
Answer #2 - Because you're dealing with an enthusiastic pruner (that's me) I'll share my guidelines with you anyway :).
If you have decided to go with answer #2, and do a little pruning anyway, all you have to is prune the three branches I circled in orange.
Why prune it anyway? Great question! And the answer is simple.
Health reasons - Citrus trees enjoy fresh air that is freely flowing close to the tree's center. It also likes to touch sun beams. And there's another consideration, which is your health and safety - you won't need a ladder to pick the fruits or maintain your very high tree (which can be a challenge when your tree is so tall).
Better yield - Both tangerine and lemon trees have a unique kind of growth, they both go up and up and... up. Sending their branches up high poses some disadvantage, which is that the tree doesn't have the energy to send everything it needs all the way up to the top of the branches in order to produce high-quality fruits at such high heights. So, keeping the canopy of the trees lower would be better both for you, and for the tree.
Follow the tree's stems with your eyes all the way to the top and you'll see where I have marked in orange the rogue branches that have climbed a little too high. I suggest keeping the canopy more or less at the red line. Cutting those very tall stems away will provide the tree with those things I mentioned above. Other than that, you don't have to touch the rest of the tree - it's perfect as it is.
Think Design - As for the green circle, well, it crossed my mind that you have such a beautiful tangerine and one of the most beautiful parts of citruses is their trunk. So, if you make just one more small cut, removing that tiny branch - it might look even better.
When to prune? - Pruning tangerine trees can easily be done throughout the year. But if it's now spring, like you mentioned, you would be better off getting it done sometime between now and until mid-spring. I wouldn't like to expose the center of the tree to too much sunlight, the branches may like it, but the citrus' trunk doesn't. And if you don't prune soon,it's perfectly fine to wait until next year (around this time of year). Don't worry about the fruits, you have plenty of healthy branches, so you can feel fully in control and decide the when and how.
Hope that helps.
And please feel free to use the comments section below if anything is unclear, or if you have another question.
Providing general guidelines on 'how to prune' any kind of plant is important, but there are plants, and there is YOUR plant. So despite there being loads of information on this site, I also provide specific and personalized support. If something wasn't clear, or you're not sure of your plant's name, simply send me a picture with your question. Use the form below and I'll get back to you. In the mean time, see what others are asking.