Dwarf Blueberries in Garden Plots

• Dwarf blueberries that are well-established in garden plots need little assistance to overwinter successfully in most of the country. Like their wild ancestors, domesticated blueberries are at home with relatively harsh winters. Most cultivars are hardy to Zone 5, and several are hardy to Zone 3. It is helpful to cover the plants with 4 to 6 inches of a loose insulating mulch, such as hay or straw, or cover them with burlap. If rabbit damage is common in your area, you should also protect the plants with a covering of chicken wire.
  
  

Move Pots Indoors

• Dwarf blueberries are well-suited to container gardening, with their compact growth and high productivity. Unfortunately, pots do not provide adequate insulation for their roots during a cold winter, so care must be taken to overwinter them successfully. The simplest way of doing this is simply to move the plants indoors. An unheated shed or garage provides all the protection the plants need, as long as there is adequate light. Windowsills or plant stands within the living areas of your house are also suitable.
  
  

Bury the Pots

• A second alternative is to provide the berries with exactly the same protection they'd receive in a garden plot, by burying your planters in soil. Select a location that offers some protection from the wind, but accumulates winter snow. Snow is an effective insulator, and a few inches over the plants is a great help. Protect the potted plants in the same fashion as outdoor plants, by covering them with a loose mulch and protecting them against rabbits if necessary.
  
  

Shelter the Pots

• The problem with overwintering plants in pots is that the roots must be protected from fluctuations in temperature. Traditional cold frames will not accomplish this, unless they are given a covering that filters out most of the incoming light and heat. A more effective cover is provided by two layers of white polyethylene plastic sheeting, available at hardware stores and garden centers, with a 12-inch layer of hay or straw in between. Anchor the sheets with large stones, bricks or other weights.