Overwintering Perennials In Pots In Harsh Climates

Planting perennials in containers is a great way to create a colorful and appealing garden when there are space constraints. Although perennials are generally hardy, nearly every one of these beauties growing in containers need protection to survive harsh winters.

Low maintenance perennials suited for overwintering

The first step is to do an extensive plant search and choose the right perennials that are suitable for overwintering. With a wide array of perennials available for sun and shade, most people are overwhelmed when choosing plants in a gardening nursery. Here are some perennials that are not only hardy but overwinter well:

  • Yarrow or Achillea
  • Lady’s Mantle
  • Aster
  • Bellflower
  • Dianthus
  • Echinacea or Coneflower
  • Chrysanthemum
  • Daylily (Hemerocallis)
  • Japanese Iris (Iris ensata)

Choosing the right container for overwintering

The first thing you need to do is to make sure perennial containers are large enough because the bigger the container, the higher the overwintering success rate. Bigger pots have a larger soil volume that helps insulate the plant roots and protects them against freezing and desiccating.

Ceramic, clay, terra-cotta and concrete pots can crack in winters as soil expands when it freezes. Keeping these pots in insulated spots is important to prevent this. Plastic and imitation clay are lightweight and can resist temperature fluctuations.

Should perennials be repotted prior to the cold weather?

It’s a great idea to repot your containerized perennials in spring when these plants are actively growing. Nourish them with nutrient-packed, fresh soil and slow-release fertilizer to promote new growth.

Overwintering techniques

Tilt the pots and bury them in your mulch pile and place them back in their original spots in early spring. Create a cylinder using hardware cloth or wire fencing and fill it with straw, mulch or chopped leaves to protect the plant from the harsh effects of freezing and thawing.

Regardless of the climate, water the containerized perennials thoroughly before the ground freezes. This will give the plants a reserve supply of water they can use during spells of warm winter.

Aster novae-angliae ‘Purple Dome’ ~ Herbaceous Perennial ~ Zones 2 – 9