I live in New England, and I have a Grapefruit tree about the size of yours. I keep mine in full sun- I start bringing it out when the temps are in the upper sixties, and leave it out at night when the temps stay in the fifties. I recommend getting a good plant caddy to make moving it easier! My tree had a tough winter, but it's budded and the leaves are more vigorous; it's leafing out a lot more- same with my Meyer Lemon tree. Just remember to water well enough during hot weather. They seem to like that too. It sounds like you'll have enough light to carry it through winter. I use a clamp on light with a plant floodlight bulb (??) during December and January to give it a little help. (Go to your local home improvement store- these things are easy to find) A little Epsom salt in the water helps too, but only during active growth- early spring, I think around late February? Good Luck! Jen

If you're growing long term in a pot you should root prune regardless of how often you increase the pot size. Basically if you don't prune, the roots get progressively thicker and woody reducing the overall percentage of feeder roots. I didn't want to buy/lug a larger pot for my lemon tree this year and decided to root prune for the first time. It was easy and the tree is doing great. Here's an old post I found on the container plant forum that explains root pruning better than I ever could. It's not specifically geared toward citrus, but I found it helpful. Here is a link that might be useful: Root Pruning Trees

When to harvest my fruit trees in a pot

I am curious to see pics. I wonder if kaolin foliar would be helpful, especially if it's too hard to move the plant? Surround WP https://cdn.shopify.com/s/files/1/0061/1391/9089/files/pmb380-b.pdf?v=16658315131648415598