Critter, here in so. Cal. every one has an avocado tree in their yard. The only way you could ever get fruit in your climate would be if you have a true dwarf variety, and hand pollinate it. Avocado trees become huge and tend to bloom in late winter. They are shallow rooted, heavy feeders, and take an average of 7 years to produce fruit. The fruit takes about a year from bloom to harvest. I have been told that if one has different varieties, one can get fruit year round, but there isn't much info about culture on the net. The only dwarf trees I've seen are as wide as they are tall and have very small fruit. I'm sure someone will deny this, but In my opinion, aside from kumquats, Meyer lemon, and a few other citrus, tropical fruit trees won't produce edible fruit in the north, unless you have a LARGE green house and hand pollinate. In my yard Lemon, Lime, and Avocado all bloom in late winter. There's a reason those darn things are so expensive!
