While there is a garlic question on the table I'd like to also ask what happens if I just leave them in the ground the entire year?

I only grow them for the flowers.

I grow a roughneck garlic, and the best time to harvest it is after the scapes have turned brown. My garlic does not bloom, it sets tiny garlic bulblets at the top of each scape. I can plant the bulblets, and it will produce a small clove next year (size of a large gumball) and planting those small cloves will produce garlic the size of a fist the next year.

If I "lose" a garlic, it will grow as a larger clump of garlic the next year. Leaving it longer than that will cause the center to rot out.

Keep in mind that there are several types of garlic, and other varieties may behave differently.

Hi Quirkpod,

I have just pruned off my scapes per the instructions that came with my bulbs. This is a portion of an article I found online. Hope this helps!

HARVESTING
Many people make a big mistake at this point. They wait too long to harvest. Keeping garlic in the ground beyond a certain point does not result in bigger bulbs, but rather dried out, split and nearly useless ones. When to harvest? When the lower third to half of the leaves have turned brown, but there are still mostly green leaves higher on the plant, it's time to harvest. Others suggest harvesting when the hardneck scapes are standing straight up but before the pods containing the bulbils open up. You can always test dig one or two plants. You should be able to see the shape of the cloves beginning to bulge through the wrapper. On the High Plains, depending on the weather, harvest can begin as early as the first week of July. There is also a two to three week difference in the harvest dates of the several varieties. So watch you plants carefully. To get the bulb out of the ground, don't just try to pull them. The stalk will break. You must dig, using a pitchfork or the like in order to loosen the soil. Then you can lift the entire plant out of the ground.
Don't let the bulb stay in the sun very long as it will sun scald, which reduces its quality. For our larger fields here at Yucca Ridge our very clever neighbor Bob has modified an ancient potato picker which actually does an excellent job at extracting the plants. (It really helps to move in next to a guy who likes to weld things and is so clever he makes you feel quite inferior, which of course you can't admit to him....... why am I getting into this?)

Incidentally, many people wonder if the scapes should be cut in order to increase bulb size? For elephants the answer is definitely yes. For hardnecks, yes appears to be the correct answer also, although some varieties seem less affected by leaving the scape attached. Cut them generally just before the scape has fully extended (or the coils in the Rocamboles have started uncurling). When still young, the scapes are considered good eating by some.