Not much to add to Danita's excellent info... agree with every word.
For short-term plantings like seasonal displays and seed-sprouting, vermiculite might not be harmful, but in a more long-term planting, vermiculite will help suffocate/rot roots because it collapses. Without any air in a pot, roots can't grow. They need oxygen and moisture at the same time. Perlite is much better for aeration. Screening out tiny particles of any kind can also be helpful. The smaller the particles, the less air there is between them. (Think of a jar full of peas vs. a jar full or sand.)
It's normal for bulbs to discard old roots, then grow new ones when disturbed... depending on the nature and length of the disturbance. This may apply to your garlic. I don't know the other plant.
I don't know your climate, but garlic needs some direct sun to grow here.
