Maybe in the blossom grove hostiles still spawn but are heavily nerfed, like creepers won't even damage the environment, and skelrtons would just be pests as their arrows won't even hurt they will just knock you back.
I really like all of those biome ideas, especially the autumn one. Especially all of them actually, I think they should be implemented into the game. Maybe in the darklands there are like subterranean or albino versions of existing mobs, which are stronger.
Everyone who says the blossum grove is too easy, he did say it would be extremely rare. Its like a secret area of sorts, a reward for extensive exploration.
throw raing fierballs and a large volcanon in the darklands biome and hey u got something. however it would be kinda strange seeing a blossom biome next to a darklands or even the wild west one, but hey its minecraft funnyer things have happend