The best time to harvest pears is when the fruit is still firm and the skin is a light green or greenish-yellow color. One indication of optimal harvesting time is when the stem of the fruit detaches easily from the branch with an upward twist.
After harvesting, pears need to be ripened to be good for eating. Commercially, pears are picked when mature, not ripe, and then cooled to around 30 degrees Fahrenheit. The Bartlett variety only needs 24 to 48 hours at this temperature, while other types need one to three weeks. The pears generally ripen in one to seven days after this cooling period. Pears are different from other tree fruit in that they ripen from the inside out; a pear that is tree-ripened may appear edible on the outside but may be rotten already at the core.