Avocado flowers pollinate mainly by wind and bees. To ensure pollination you should have more avocado trees. So it always recommended to plant more than one avocado tree in the garden.

Also development of fruit from flowers depends on weather condition (ideal temperature 65 - 75 F). Too hot or too cold will kill the flowers.

For pollinating your tree bring branches with bloom from neighbors' trees (if they willing to give) keep them in buckets (with water) under your tree or strap the bloom along with jar of water in between the two branches of your tree.

To know more about avocado flowering please see the following link http://ucavo.ucr.edu/Flowering/Flower...