I got a response from an herbalist on Michael Tierra’s forum which I’ll share:
1. Given that this will be a combination of a half dozen or so herbs, how do I decide on the alcohol content of the vodka to soak them in?
You would take an average of all the combined herbs and their alcohol ratio’s to decide what menstruum to use. Typically vodka is around 40-60 proof, so that is fine to use straight with the herbs you have listed below.
2. Is there any reason NOT to use powdered herbs?
You can use whole or powdered herbs.
3. If I do use powdered herbs, is it okay to simply leave them in the vodka the whole time (5 months) I am taking the tincture? (Rather than straining them out after a month or so.)
Yes, you can leave the herbs in the tincture, although as you start to get past the middle of the total volume, I would strain.
4. The herbs I definitely want to use are astragalus, Siberian ginseng, and ginger. Others I’m considering are: rosemary, cayenne, garlic, turmeric, ashwagandha, What am I forgetting?
The herbs depend on your constitution, so using that as your baseline decide what herbs you need. Elderberries can be a good addition.