Some vines may be cut off but allow fruit to set, then cut off the vine beyond the last fruit. Harvest immature summer squash while the rind is easily punctured by a thumbnail. Zucchini and crooknecks should be 6 to 8 inches long and 3 inches in diameter. Scalloped or patty pan squash are harvested when grayish or greenish white but before they turn ivory. Harvest spaghetti squash when the rind turns golden yellow.
Banana squash is harvested when golden orange.
Winter squash ripen on the vine and develop their characteristic color before harvesting. When ready, the rind is hard enough to resist puncturing by a thumbnail. Harvest before hard freezes, take 2 to 3 inches of stem and avoid bruising the fruit. Squash harvested with a stem left attached store best. The first blossoms are male so incapable of setting fruit.