I've had mixed results. Put a 'Redhaven' and a 'Mericrest' in the same hole. They were compatible in vigor, but the Mericrest was unproductive, so I cut it down. I would chalk that one up as a 'win' Better I didn't waste a full hole on Mericrest, and it didn't seem to slow down 'Redhaven' Other hole had 'J.H. Hale' 'Double Jewel' and 'Fantastic Elberta' Double Jewel bore really well once, then stunted out. I cut it down. 'J.H. Hale' appears to be a good tree, but it is too feeble to compete with "Fantastic Elberta" FE finally pulled through for me last season, but I wish J.H. Hale had a prime hole. Shoulda done a little more research about the characteristics of 'Hale' on that one. 'Geo-Pride' Pluot was shared with 'Elephant Heart' plum. EH died immediately. GP bears very lightly in Z5A and it is now shaded too much by some of my other trees. I would put that one as a wash. 'Shiro' was shared with 'Red Ace' Red Ace died immediately. Shiro bears even more lightly than Geo-Pride. But its a pretty tree close to the house. Another wash. 'Polly' on the other hand was given its own hole based on my supposition that it was a prime candidate to be a good producer. It turned out to be true. I guess my conclusion is that shared hole planting has been useful to me to try different varieties in limited space in a marginal climate. So I guess I would recommend it, but pay attention to relative plant vigor, not just any peach with any peach, or any apple with any other apple.

Schnell: I know of two people who have orange trees like you describe. I know a lot more that have planted seed from supermarket oranges that have something else they can not eat. I have a couple of grafted trees that give small sized oranges. But I wonder if your trees are truly "round oranges" or if they may be mandarin hybrids, like Fairchild, or Sunburst? I have seen a lot of people surprised to find out that Page and Satsumas for example, are not "oranges". If you have some mandarin variety, they may be as big as they can be. If you have some true orange, thinning and fertilizing may increase the size somewhat. On the time to fruiting from seed, a general rule of thumb is the smaller the fruit the sooner seedling tree bears. But there are big differences in the results you can get. I planted a Rio Red GF in a really good soil with a fantastic mulch, and it fruited in only six years. I planted a Ray Ruby seedling near a giant pecan tree in heavy clay, and it is 13 years old and has not bloomed. Getting them to bear is a function of getting them to outgrow the immature wood. A lady once said she had a Keraji (small mandarin) that was 9 years old that did not bloom. Mine had fruit in four years because I had it in a good raised bed and it was well mulched..

I have a dwarf orange tree in the ground in full sun here in AZ and I water it fairly rarely actually, at most once a week, but when I do water it, I just let the hose sit there for a long time and it gets a heck of a lot more than 7 gallons. So far it seems to be doing good. (it's still a baby, very small). The best time to fertilize it would have been about a month ago, but right now is still a good time, so yes I would water it really good, then fertilize it (not any closer than 2 ft from the trunk though) and give it another good soaking, Then I'd leave it alone for a week. Maybe repeat the deep watering after one week. Then you can cut back on water (meaning, still continue to water deeply, but you don't have to overdo it as much). That's just my 2c. And let us consider ourselves lucky that we can have these citrus in the ground. Oh, and some gypsum with sulphur in it would probably do it some good. (the brand I got last time had sulphur in it, which is nice to kill 2 birds with one stone.)

Linda, I am afraid that I have tried many applications of Meyers and never like the result, in complete contradiction to John and many others to me anything that has a Meyer in it would be better with a traditional lemon. Meyers have a "dirty" taste most of the time and at best have a weak orange flavor. I cannot tolerate drinking anything with Meyer in it, or any fresh application. I have made cakes, curds, pies, lemonades, fish with lemons cooked or grilled on top, etc with Meyers and never particularly like the result, though cooked they are more tolerable then anything with the fresh juice. However I had to toss out the salmon I made as the orange undertone flavor was awful. I just tried a jar of preserved lemons I made with Meyers and they were very bland compared to traditional preserved lemons. I keep trying to like them but I haven't found anything I prefer with them in it yet, mostly just things I find less offensive. I used to cook professionally and used Meyers pretty consistently in many applications and still never cared for them (same with kumquats though I REALLY don't like Kumquats and don't even want to try them in things anymore). I am pretty sure I am a traditional lemon kind of girl, which means more Meyers for the rest of you that like them! ;) Also I agree that its likely that your rootstock is taking over, cut off any branches that have different fruit and take note if the leaves look different in any way to your orange, that way you can identify it earlier and remove branches before they fruit and steal energy away from your oranges. Take pictures so if it happens again years from now you won't be struggling to remember what they looked like. Its likely that your neighbor had a tree whos scion died back/was taken over by its root stock at some point. If your friendly with them and they are the ones that planted the tree ask them what kind of tree it was when they planted it and if it changed at any point. If they didn't plant it they may not know. If you show us a picture of the tree we could help you figure out when to prune it.