WowAce

I see nodes for Bloodpetal Spores but not for Un'goro Soil, which is much more useful to locate. I was doing the quest Bungle in the Jungle and Questie showed the soil nodes until I collected enough needed and then they disappeared, so you could initially populate the data with that from Questie, if it's not already in your regular data source. 

GatherMate2 for Classic is now at https://www.wowace.com/projects/gathermate2-classic

To enable Un'Goro Soil (and any others)
Navigate to the addon's location in the WoW Addons folder.
something like: C:\Program Files (x86)\World of Warcraft\_classic_era_\Interface\AddOns\GatherMate2

Then open the "Constants" file
Ctrl+F: "Un'Goro" then remove the two dashes 

--[NL["Un'Goro Dirt Pile"]] = 511,

to

[NL["Un'Goro Dirt Pile"]] = 511,

Then Ctrl+F for "soil"

Remove the two dashes.