Hopefully now that I am posting this, the fruits will not fall off and make an A $ $ out of me. But I thought I would post my findings in hopes that it might help others.
In the 5-6 years prior to this, I have boughten orange trees while in Florida. All had fruit already on them. However I could never get fruit from them MYSELF. After picking the last fruit, they never rewarded me with another one. In zone 5, of coarse I had to bring in the Orange trees inside from the Winters. I THOUGHT I was doing the right thing by putting them in a bright spot by a window. I THOUGHT the sun and the warm temps would be great for them. However, EVERY YEAR, they would drop every last one of the leafs and then in the spring grow new LIMBS and flowers, but never would hold fruit past a pea size.
While reading on a citrus board that I can not now find for the life of me 😳 I found that Oranges actually need a "cooling off". I read that what I was doing was the exact OPPOSITE of what us cold zoners are supposed to do.
I read that I needed to put the tree in the unheated garageand totally leave it alone, only watering maybe once a month if that much even. All thou I thought it sounded stupid, after losing so many other trees, I thought what the heck. So I put it in my unheated garage and forgot about it. In December I checked on it to see if I needed to water it. I saw that where usually by December, I had lost about 20 leaves, this time I had lost...ZERO. So I watered sparingly. In February I once again checked and usually I would have only about 10 leaves still on the tree, now I still had a tree full of leaves. By the end of Feb. I had lost FIVE leaves. So in March I set the tree outside and put my usual cow manure on it and within two weeks I was seeing new leaves and branches and flowers. However there was more than usual compared to other trees I had. Also, the flowers that fell revealed fruits that were staying on longer. And now longer has turned into the by far the biggest beginning oranges I have EVER gotten.
So for you Orange growers in cold zones like me, give this a try this Winter and see. Here is a pic of mine today (6/26). Kinda hard to see all the fruits but they are there. The largest one is about the size of a Ping Pong ball.