If you grew perennials in containers this season, and they aren't hardy for your area, here's what you need to do with them this winter. Spoiler alert—pitching them might be the easiest solution. There are ways to overwinter some of them though.
Try not to be a hater because some of us just don't have the right situations (or patience), but often perennials in containers are treated as annuals and are tossed out in the winter season. New plants replace the old in the spring. However, perennials can survive the winter with some preparation and care.
How to Keep Perennials in Containers Over the Winter
Container perennials rated one or two USDA Hardiness Zones colder than your area have a good chance of living throughout the winter outdoors. For plants not hardy to your area, you have a few options.
1 You can keep them in an unheated interior location, like a garage or a cold frame, making sure they do not dry out completely.
2 You can identify warm microclimates in your garden and try one of the following techniques: Plant the container in the ground just before the soil freezes, with the rim of the pot right above or at the soil line. Cover heavily with mulch. Or remove the perennial from the container and plant it closely together with other perennials in the soil, also adding heavy mulch.
3 A riskier option is to tightly group all the potted perennials (still in their containers), pile heavy mulch over the top and hope for the best. The best location will be one that’s sheltered from wind and strong sun. It may seem counterintuitive, but up against a north-facing wall or hedge is a better choice than a south-facing wall or hedge. That’s because the north wall will stay fairly consistent in temperature, while the south wall may warm during the day and cool drastically at night. This swing can harm the plants.
4 Select container that can survive freezing temperatures. As the soil in the pot freezes, it will expand. A pot that’s not durable may break under the pressure. Fiberglass and plastic pots are least likely to break. Terra-cotta, ceramic and concrete pots may survive the winter; the thicker their walls, the better their chances.