Tips for overwintering plants in containers
Select a frost-proof
container. Choose a pot with a drainage hole in the bottom and made of fiberglass, lead, iron, heavy plastic, or stone. Most terra-cotta will crack in cold temperatures, but I have had luck with glazed pottery.
Use a good potting soil. There are mixes specifically made for use in containers, which provide the essential drainage that plants living in pots need.
Stop feeding in fall. If you use a water-soluble fertilizer, stop feeding your plants about six to eight weeks before your first frost date. This will prevent any tender new growth, which wouldn’t survive the winter. Begin fertilizing again when the plants resume growth in the spring.
Water into winter. Water as needed until the soil in the container is frozen. Do not water frozen pots because the plants are unable to absorb the water.
Apply an antidesiccant. Use products such as Wilt-Pruf on broadleaf evergreens and conifers to protect against damage from winter winds.
Repot every few
years. Though some plants will live longer in a container, repot your plants every three years to be on the safe side.