Hey k Bunny,

I used to live in the southwest and i have taken care of orange trees quit a bit. In Arizona many folks historically planted what are called ornamental orage trees. This was due to the fact that these type of orange trees are more frost tolerant that the paletable variety. This notion was later abondonded and people started experiamenting with other types of citrus trees and you can generally find all kinds of citrus tree varietys in the southwest. Alot of people either cover their trees in preparation for a frost or put up christmas lights in hopes of adding just enough eat to avoid severe frost exposure. Its hard to say whether you have a palateabe variety or not, but i guess ultimately the proof is going to be in the pudding.

Regardless of what type of tree you have, catering to the trees needs is going to directly influence the quality and quantity of fruit that it produces.

I'm not sure if you have frost concerns living in LA but i'm pretty sure you have limited precepitation there and orange trees require a TON of water. They are not considered a environmentally concious crop outside of places like Florida where rain is plentiful. As a consequence you will need to make sure that you water your tree quite frequently and especially durring the hot parts of the summer. That is if you want to get some decent fruit.

You'll also want to fertilize the tree three times a year to insure adequate fruit production. I'm drawing from memory here but i think the rule of thumb says fertilize on valentines day, labor day and memorial day. You can get a product like Vigro for citrus at your local hardware store but an organic fertilizer would be a good idea too. Adding a heavy layer of compost and mulch under the trees canopy would be a good way to keep it healthy and help in water retention.

If the fruit is still bitter after that, i recommend you make some marmelade, can it and give it out on christmas! ;)

I have a variety of citrus growing on my place, and most of them have thorns. I don't think it is an indication of predisposition toward being sour.

as a gardener and tree-pruner, I can confirm most citrus (ok ALL that I have ever seen) have thorns, not just sour oranges. you can snip the thorns as you find them, thereby reducing the wounds inflicted upon you during future explorations in the canopy...