Damn changes to herb growth. I did so much work and used so many seeds ... all wasted. At least there's a wiki.
EDIT: Hmm, I take that back. One of my surface-planted blinkroots just bloomed. Maybe the cycle has just been slowed down. By a lot.
EDIT2: Oh, there's a definite difference between growing a plant in its biome versus growing it elsewhere. (See below.)
EDIT3: I read through the code last night and this morning... didn't see any biome tests. I'm confuzzled.
EDIT4: Final results of discovery. There are NO biome checks on player-planted herbs or on herb growth. Only the base block type matters.
Daybloom, moonglow, waterleaf, and fireblossom are all forcibly made to bloom under specific conditions.
Blinkroot's second stage of growth (mature to blooming) has slowed down a lot. There's no obvious reason in the code, that I can see... I think the grow-plant routine is just called less often.
The gamepedia wiki has just been updated to say that shiverthorn's maturation cycle follows the same rules as blinkroot. My analysis agrees with this. It also says that the cycle is slower than blinkroot's; I disagree. I think it's the same rate, it's just that blinkroot's cycle has also been slowed down.
Note that there also many less valid locations for game-generated herbs to grow. This is because so many blocks are now shaped, especially underground.