What are the pros? well, you can't kill it
What are the cons? pretty much everything else
Herb my fanny. More like invasive species. Mugwort is a weed. As in, plant this in your garden and watch it invade the root systems of your beautiful vegetables, shrubs, perennials, and what have you. I don't think it's fair to sell this stuff without a warning, as it will take dose after dose of roundup to eliminate it from your garden once it is established. I am a professional horticulturalist, and I have had to dig up entire perennial beds because the roots from a mugwort plant crept 30 feet through two stone walls and into a client's perennial bed. We have spent 4 years trying to eradicate it since the client first called us. Leave one piece of the root--one teeny, tiny piece--and the entire plant grows back. If you want to grow it in a pot, fine, just don't let it go to seed. And if you must put it in a bed, at least warn your neighbors so they have time to pave their entire property, because that's the only thing I can think of that will keep it at bay.
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