I have several large pots of perennials and small shrubs that I would like to save. The only indoor space I have is the laundry room, which has no natural light. I was wondering if I could put them in my garden shed under blankets?
This is a challenge every fall for those of us who love to grow in containers. Here’s the basic issue: it is usually the freeze/thaw cycle that kills the plants, not the initial freeze up. So container size is important. The more soil there is in the container, the better. In a large (at least 18 inch x 18 in by 18 inch) container, there may be enough soil that it is unlikely to thaw out in your shed during the occasional warm day we have in the winter. Unfortunately, if it is a clay pot,though, the pot itself may shatter when the moisture captured in it freezes.
Ideally, if you have a bare spot in the garden, perhaps a bed that you had filled with annuals, you can “heel in” your perennials, that is, plant them out in the bed, and in spring, dig them out and repot them. I do this with many perennials and small shrubs, year after year.
Or you can try putting your non-clay containers, surrounded by soil, inside other, larger containers, grouping and covering them with leaves as we described in our response to another such query, which you can see here.