I've always heard you're supposed to flip your mattress about every six months. Nothing to do with summer/winter sides, supposedly it's to prevent sagging since we tend to sleep in the same spot all the time. Same thing for rotating, I guess? It doesn't appear to make much difference. We rotate our mattress about every other changing, and flip every six months or so. I used to be able to flip it by myself, but now I search out my husband to help and between the two of us we get it done. As I said though, I don't notice any difference, the mattress is supposed to be extra firm but but the firmness doesn't stand up anymore. After we got it I wished we'd kept the older one. It was firmer and wasn't made to be flipped. Oh well.
Any time we've gotten a new mattress the delivery guys have taken the old away. The last ones told us they send them to be recycled (
not re-used
) at a place that manufactures mattresses. At least that's what they've said. I think next time we need one I'll check into the ones you can order online that are rolled up in a box... But then what to do with the old one? Always problems...