Yes, you can harvest the honey from the filled hive to turn it into a honeypot now. To have a honeyblossom flower you need to plant a honeyblossom seed in a honeypot - the seeds are stored on the Misc tab in the seed shop if you have any. If you don't, you earn them by spotting multiples of each colour of bee in other gardens - check the wildlife guide to see how many you need of each colour.
This thread may be useful:
https://www.fairylandgame.com/fbfairy/forums.php?tid=116959