Feel free to laugh at anyone who brags about eating ripe Bosc pears just off the tree. Bosc pears (Pyrus communis "Bosc") do not ripen well on the tree but must be picked immature and chilled before they are ripe. Gentle pressure on the neck of the pear tells you whether it is ready to eat.
A Pear of a Different Color
The Bosc is not your quintessentially squat pear, like those often pictured in trios in a kitchen window. It is browner than yellow, with cinnamon russeting appearing over its dark skin. Its neck is long and lean for a pear, making it look more elegant than cute; it is crunchy and sweet with a hint of spice. Bosc pears will be ready for harvest in late August or early September, but you want to take the necessary steps to ripen them before sinking in your teeth.
Boscs on the Tree
The European pear species that produces Bosc pears doesn't grow anywhere in the wild. It was developed in either France or Belgium in the 1800s, and takes its common name from a director of the Paris Botanical Garden named Monsieur Bosc. Imported to the U.S. some decades later, Bosc pears are a popular commercial and garden fruit tree. They grow best in full sun and well-drained soil in U.S. Department of Agriculture plant hardiness zones 5 through 8. Generally European pear cultivars are grafted onto hardy rootstocks. One of the "winter" pears, Boscs mature on the tree in fall or early winter, but do not ripen until picked.
Ripeness Is All
Your Bosc pears should be ready for picking in the autumn, generally over a period of two to three weeks. Don't chomp into one to see if it's ready. Since these pears ripen from the inside out, the core will rot before the outside flesh is ripe. You want to harvest them when they are "firm mature." Most pears separate from the tree when you tilt them to a horizontal position, the so-called "tilt test," but Boscs do not. Instead, pick Boscs when the hard pears begin to fall off the tree.
Harvesting and Storing
Once you have removed the Bosc pears from the tree, place them in cold storage at about 35 to 45 degrees Fahrenheit for several weeks. Pears do not freeze at that temperature because of all the sugar in them, and the longer they spend in cold storage, the shorter the time to ripen. If you don't chill Boscs, the mature pears will rot without ever ripening. Once the chilling period is completed, the pears ripen after 5 to 7 days in temperatures of 65 to 75 degrees Fahrenheit. You can tell if they are ripe by using the pressure test: Place your thumb against the pear's neck and press. If it gives slightly, your pear is ripe, though according to USA Pears, the website of Pear Bureau Northwest, this "give" is less than that of other types of ripe pears.