d olives, by moving them into unheated greenhouses in fall. You can also employ the "eavesdropping" treatment favored by Benowitz: Move containers under south-facing eaves and drop a sheet of plastic down from the eaves to create an instant greenhouse.
Hardy fruit trees shouldn't suffer damage if temperatures fall below freezing at night for brief periods. You'll need to protect root balls from freezing, however, if we have daytime freezing temperatures.
Home Orchard Society
"The Bountiful Container"
Rose Marie Nichols McGee and Maggie Stuckey
Workman Publishing, 2002
Western Garden Book of Edibles
Editors of Sunset Books
Oxmoor House, 2010