Immersive Weathering and The Undergarden are two very fun mods, and although currently they don't interact together too much beyond falling leaves, this data pack changes that.
How? Well it uses new block growth jsons to do several things:
> Deepturf and Shimmerweeds grows out of Deepturf Blocks, but do require existing Shimmerweeds to be nearby.
> Deepturf and Shimmerweeds also grow into their tall variants.
> The Undergarden's forests slowly grow new trees.
> Deepturf now gets burned into Ashen Deepturf if fires get lit near it.
> Some other plants may grow out of deepturf blocks. Mostly beans.
> Gronglets become plentiful on Grongles with a low amount or no Gronglets.
> Not lag your game (this is surprisingly not resource intensive).
I can't show you it working on it's own on this page, but trust me it does work, if you have Immersive Weathering (Forge) and The Undergarden installed of course.
If you need to disable a feature or want to learn from this, you can unzip this datapack mess around with the jsons included.
You can use this or derivative datapacks in modpacks/servers as long as this page is linked back to.
If you want to provide feedback or report issues, give me a big mean ping on the Undergarden discord.
