Given the right conditions, the growth rate can be moderate to fast. There are many people who view Opuntia as a weed and are trying to get it out of their yards. It's understandable for people with children or pets not to want it. Last season was the first time I planted Prickly Pear and i expect it should flower within a year or two.

Here's a link to more info

http://www.floridata.com/ref/O/opun_hum.cfm