Spent a considerable amount of time growing & manually cutting down 20+ Mangrove trees surrounded by the maximum flowers possible (5x5 with the Propagule in the middle) as I was also needing some Mangrove Logs for future builds; basically "2 birds, 1 stone" kind of deal, I thought to myself.

After getting a bit fed up with no Bee Nests, I just went ahead & gather Apples from Oak trees instead, & what do you know? It took only 2 tries in the same flower setup.

I also tried the 3rd & last option, the Birch, & got a Bee Nest in 4 attempts.