Answer: I have moved away from my own gardens so I understand how difficult and wrenching it can be. But to be honest there are three important cautions here. First, if your house is being sold the sales contract may not allow you take your plants. Second, holding perennials over winter can be very risky. Third, your plants may or may not survive when planted in your new location, depending on whether or not they are adapted to the new growing conditions.
Having said all that, you can try lifting them and putting them into pots as they go dormant and storing them in a protected but cold location such as an unheated garage. Try to maintain a fairly steady cool temperature so that they stay dormant. Keep an eye on them. Keep them rather dry so that they do not rot but do not allow the soil to go completely dry. In early spring, move the pots outside into a sheltered location so that they can begin to "wake up" with the normal season. Plant them out as soon as you can.
Another approach would be to transplant them to a friend's garden now and leave them there for the winter. Then move them again in the spring when you are ready. This is probably the less risky choice.
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