You just gather all the different plants in the inventory of the character with alchemy skill, make sure that character is "leading", then right click on any of the alchemy herbs and a menu will come up. The menu will have the options you can use in gold, the ones you cannot use in gray.
Which brings me to a rant about permanent potions. I blew 4 precious skillpoints points on alchemy just so I could create permanent potions whenever I was able to find the correct herbs for it. All you need is the Holy Water. Perfect. I was able to create lots of permanent potions... and yes, I saw that instead of giving only 1-5 permanent points, there was a bug that allowed each potion to give up to 20 permanent points. I figured that would be fixed in 1.42 since the ReadMe said it was fixing permanent potion bug.
To my horror, the patch fixed it, all right. There is only one Holy Water in the game. Now that Holy Water will allow you to make only one permanent potion, which in turn gives you one permanent point, then it disappears. WTF? For that I'm supposed to use up 4 skillpoints? I don't think so.
Alchemy has just hit my list of useless skills, right next to lockpicking. Bah.
