Not sure if the skillblooms are really that worth it for a resource that right now in nutaku is pretty slow to get.

They give you an extra percentage of Skill activation rate and nothing else, but it's really small like 4% or something , i don't remember, but if they were dress blooms instead then i would definitively consider them worth it.
I use Life Crystals to buy petals for blooming since there's at the moment no other way to get them.
For flowering hearts i would use the whale medals.