Unlike other deciduous fruit, most pear varieties (except some of the early season ones) won’t ripen properly on the tree, but need cold storage for a period of 2–6 weeks, followed by a period of ripening out of the fridge. Pears ripen from the inside, and ripening them on the tree leads to both poor texture—either grainy or mushy—as well as poor keeping qualities.
Read the article in Autumn – Week 5.