How do I grow avocado in Seffner, Florida?

You are in Zone 9b.

"Avocados are not native to USDA zone 9, but yes, they will definitely grow there. ... West Indiesavocados are more commonly found growing in Florida, as they are the most salt tolerant and least cold hardy. So when choosing zone 9 avocados, look for Mexican or even Guatemalan avocado varieties, hardy in USDA zones 8-10."

Were I you, I would google "growing avocados" and research the pros and cons before I set about to grow them.

The same with Mangos!

Thank you Jeanette. I didn't want to start growing a few trees and a few years down the road a hard freeze Kills them all..