From your description of its behaviour I'm wondering if it is actually garlic or one of the wild Alliums which can be very persistent. Can you get an accurate id by posting a picture on Name That Plant Forum? A non-chemical solution would be simply to dig over the ground and remove the bulbs by hand. On the other hand If you are going to put in a patio won't you be digging a foundation and concreting over the area anyway?

Put a "Free" posting on Craigslist that offers free garlic for the digging. If you live in an area with active Craiglist community, you will probably be swamped with emails.

I am still wondering if it is actually culinary garlic judging by the description. Could you post a picture for us?

I do not think that smell of whole garlic ,outside, in the garden , can penetrate into the house through the foundation walls, ... to the point of becoming offensive. People keep garlic in their kitchen(along with onions) all the time. The smell is released when the clove is cut or crushed.

I agree with florauk. It don't think what you have is the type of garlic you get at the store. Especially because you say it disappeared for a few years then came back. It sounds like an allium that reproduces by seed and those dormant seeds are what sprouted and grew. A picture would certainly help.

Rodney

This post was edited by theforgottenone1013 on Mon, Jul 8, 13 at 16:01