Experience has shown that getting an herbalism kit in past Dungeons & Dragons campaigns I've been in doesn't usually lead to much of anything during actual game play. There's always the character that is really interested in making potions by nature, but somehow the game forgets they even exist once it gets going. So for homebrew sake, we're going to say anyone that has a herbalism kit is subject to whatever homebrew rules it takes to brew specific things in specific regions of this campaign setting. There will be DC's to roll against, with bonuses for anyone who has related skills or backgrounds and there will be component gathering and long rests spent brewing.
Our experiment with this starts in Goldvale, where player characters may collect specifically noted herbs/components to make potions with, which will have specific effects. All Goldvale based potions will use 2 components that determine the type of thing being crafted, and a third component of anything locally available will determine the duration or strength of a crafted potion. The later element of duration/strength won't be known or recorded here until someone has experimented with it at least once. The name of everything is a huge hint as to where the component can be found in the greater Goldvale area. Please note that nothing here creates a healing potion, as not to overlap with the most common game potion. And as far as Goldvale goes, Kori is probably an expert about this stuff NPC wise.