You should probably top them. Look it up, and explore the board a bit. There are plenty of answers on this board - treat it like an encyclopedia; but, take it with a grain of salt, unless you have someone who has been around passing on some insight from experience. Experience counts a lot - learning the hard way really impresses a memory upon ye ole noggin'.

Also, you just said they were nearly 6' tall, so they must be getting plenty of sunlight. Flowering normally starts outdoors when the days become 12/12 light/dark. It may take quite a while to determine sex, but there are some threads on this board that will help you find a few early indicators - use the Search function.

Be good out there.