I've learned, this summer, that with certain things (potatoes, garlic...), when they start to look ugly and sickly it means they are ready to harvest. Our garlic was looking pretty funky (and I happened to notice that farmama had a garlic post up) so I started carefully digging them up. They were all ready. It was real exciting. We got well over 30 heads of garlic from a little 3x3 patch.