This year, I swear we're going to get it right. Pears are really tricky to ripen properly, unless you grow Bartletts, which can actually ripen on the tree. That's what most people have, so I've never actually met anyone who could tell me how this all works.
Finally, I read this great article from Oregon State University about the cold storage requirements of different varieties.
We have an heirloom variety called White Doyenne. It was once a major commercial variety, but it is very susceptible to fire blight, so when varieties with improved resistance came out, its popularity declined. We don't get much fire blight here in New Mexico, so I thought we'd try it out.
I knew that these pears had to be picked green, otherwise they will rot on the tree. It turns out that most varieties, such as Bosc, D'Anjou, Comice and many others, also need to be stored for a period of time in cold temperatures before they even develop the capacity to ripen. The cold stimulates the development of certain compounds that cause ripening. In fact, if you have a period of cold weather toward the end of the season, it can cause premature ripening, which is a problem for commercial pear growers.
Commercially grown pears are stored at 31F for a period of one to four months before distribution, after which they can be ripened on the counter the way we're all used to doing. This article from Washington State University actually describes the results of storage at temperatures of 40F and higher on ripening, and it turns out the optimum temperature for quickest development of ripening capacity is 50F. Pears that need a month at 31F only need a couple weeks at 50F. Of course, being ready to ripen earlier means you actually can't hold them as long. Fascinating stuff! I actually kind of wish that was my job, to study pear ripening.
So, I checked the temperature of the drawer at the bottom of my fridge, and it is actually just about 35F, so I should be able to hold them for probably three months. The plan is to take a few out and try ripening them on the counter after about a month, see how it goes, then maybe wait another month and try another few, to determine how long this particular variety needs for cold storage. And it's important to check them periodically to make sure they're not going bad, because we've had that happen too - open up a bag of pears that's been in the fridge only to find they've all rotted.
Wish us luck!!