Zone 3 Information
Zone 3 climates are located in parts of Alaska, lower Canada, and along the upper U.S. border. Though it stays cold for a good part of the year, you can still plant a large variety of plants in mid-April. If you are planting bulbs, do it by early September to be safe from heavy frosts. Take care to protect your plants with tall borders and shady trees as brisk winds tend to dehydrate plants growing in the frozen soil. Water everything in late autumn so plants don't dry out from the wind.
Zone 3 was divided in 1990 into two areas by the National Arboretum to provide gardeners with even more environmental detail: 3a and 3b.
3a - Minimum temperature of -40 to -35 F (-37.3 to -39.9 C) Places like International Falls, Minnesota and St. Michael, Alaska.
3b - Minimum temperature of -35 to -30 F (-34.5 to -37.2 C) Places like Tomahawk, Wisconsin and Sidney, Montana.
Here's a partial list of plants that thrive in Zone 3
Buffalo Juniper(Juniperus sabina "Buffalo")
Eastern Pyramidal Arborvitae(Thuja occidentalis 'Pyramidalis')
Amur Corktree(Phellodendron amurense)
Sugar Maple(Acer saccharum)
Chinese Elm(Ulmus parvifolia)
Burning Bush Euonymus(Euonymus alata)