Garlic is a bulb that spreads by generating bulbets (cloves).
What would happen if you planted a clove of garlic and then just left it there for 3-4 years?
It would slowly spread outwards over time with a mass of plants all clustered together. Just like daffodils etc.
It will grow based upon the environmental conditions. It's literally one of the easiest crops to grow because of it. You can plant it in July and if it's hot it will remain dormant for a month until cooler temps.