According to the following link

http://faq.gardenweb.com/faq/lists/seed/2002114535011263.html

Will my tree ever grow fruit? Sometimes they will begin setting fruit after they are three or four years old. It helps to have several avocado trees growing together to aid with pollination.

What zone are you? I am thinking of growing avocado too.

When I was in elementary school I started an avocado from a pit. It grew to be about 30 ft tall and we had the tree as long as my parents lived in that house (until they retired). In all that time the tree produced one fruit.

writersblock has it. Is this a tree you purchased?

If you started it from seed (pit) then you are looking at umpteen years (7-10 is normal and at best) before you'll see fruit.

If you purchased this plant from a reputable nursery you should get fruit in 3-4 years. It's rare to get much fruit before then. I had an avocado tree that produced at 2 years. It gave me 3 fruits. I have another that is 3 years old now and gave me 5 or 6 fruit this year....the other one that produced last year at 2 did not produce this year at all.

They take a long time to mature. Hang in there. Also spring fertilizer should be lower in nitrogen than summer/autumn.

Good luck!

Barbie~

avocados fruit on "mature" trees. By grafting you trick the tree into thinking it is old (mature) enough to fruit. Barbie is right that if grown from a pit 7 years if you are lucky.

There is also the baseball bat treatment: on larger trees that refuse to flower/fruit give the trunk a couple of good whacks with a bat...don't damage trunk! The tree thinks that might die/stress and it acts on that and flowers.