WinglessAngel, look for the threat titled "Advice for first time onion grower? " We just had a good discussion about onion culture.
I believe for garlic, if you want nice multi faceted bulbs, you should plant nice large cloves in the fall. Harvest the garlic in summer when the tops start to turn brown.
Save the largest cloves for planting next year for the largest bulbs. Cut the scapes off when they make one circle and eat them.
If you want nice bulbs, I will not recommend leaving it in the ground for growing next year. Nor will I recommend going for seed. Nor will I recommend planting garlic seed. (Unless you want to do it for the experiment)