Friday, November 11, 2016

Overwinter Your Container Plants by Donna Duffy

Photo courtesy Pinterest

It’s the time of year to start thinking about how to overwinter perennial plants that have been happily growing in containers this summer. Containerized trees, shrubs and perennials are subject to Colorado’s winter temperature fluctuations, drying winds and freeze-thaw cycles. Planttalk Colorado provides the following suggestions to get your plants ready when the first hard freeze arrives.

Following are two methods of overwintering containerized perennials: 

Container plant sunk, ready to mulch, photo courtesy Wild Green Garden Consulting
  • In November after soils have cooled, locate a protected area in the garden. Sink the plants - pot and all - into the soil. Make sure the pots are well watered and then mulch six to twelve inches deep with straw, leaves, hay, or shredded bark. The roots will be protected by the moderating effects of surrounding soil. Check the pots monthly throughout the winter and water as needed.
  • If sinking the pots in soil is not possible, cluster containers together in a protected site under the house eaves on the north or east side. Place larger pots to the outside and smaller pots to the inside of the cluster. Water pots well, then mulch heavily with straw, leaves, hay or shredded bark. Provide a thick layer of mulch or bales of hay around the outer edge of the cluster. Also, mulch over the top of the pots to lessen the impact of root-killing temperature fluctuations. Check every two weeks and water as necessary.
    In the spring, remove all the mulch and packing when the plants start to show signs of growth. It’s best to remove mulch gradually to let the plants become accustomed to temperature changes. 

    For additional information about container gardening, check out the CSU Extension's Container Gardens.