If you live around communities such as Alaska’s Bettles or Fort Yukon; Yukon Territory’s Dawson; Northwest Territories’ Fort McPherson; or Yakutsk or Verkhoyansk in northeastern Siberia, then your USDA plant hardiness zone is One, the harshest.
This means thirty-year average minimum winter temperatures are an extreme -50 F (-45.6 C) or lower. The territory is treeless tundra where conditions for growth are harsh but suitable for plants such as the Lapland Rhododendron.
According to PBS’s The Victory Garden, USDA plant hardiness Zone One is ideally suited to plants native to the most northern areas of the northern hemisphere.
Where is Hardiness Zone One?
The zone generally straddles the Arctic Circle above 60°N with its coldest regions in the most continental parts of the world. In January of 1885, for instance, observers recorded a record low of -67.1°C in Verkoyansk, Russia. Snag, Yukon Territory, holds Canada’s officially lowest recorded temperature of -62.8°C.
Zone One’s association with very cold and stormy interior continental-type climates restricts it to the northern hemisphere. Continental climates do not occur in the southern hemisphere due to the absence of a land mass large enough and far enough away from the oceans and its currents to generate this effect.
As a compensation, however, as pointed out by the Missouri Botanical Garden (MBG), “continental climates exhibit a rapid and sustained rise in temperature in spring, promoting growth of plants and greater seasonality.”
What are Hardiness Zones?
Hardiness zones consist of defined geographic regions, most commonly based on USDA criteria that support specific plants, flowers, and trees. They typically define a minimum range of temperature that a plant or tree can survive safely.
If possible it is advisable to consult other planting-related maps such as first and last frost dates, and heat zones.
Canada’s Zone One Regions
In Canada, USDA Zone One includes the tundra islands of the extreme north, the interior of the Yukon Territory, and northern Alberta. Canada’s self-explanatory designation for this area’s affinity to plant growth, however, is a designation of Zone Zero, meriting either ‘a’ or ‘b’, with ‘a’ being ‘more harsh than harsh.’
Zone One Regions in the United States
We find USDA plant hardiness Zone One in patches in the northern and central interior of Alaska including the hinterlands of Fairbanks.
According to PBS’s The Victory Garden the following plants grow well within hardiness Zone One:
- Crowberry (Empetrum nigrum) is native to most northern areas of the northern hemisphere.
- Dwarf birch (Betula glandulosa) is native to North America.
- Lapland rhododendron (Rhododendron lapponicum) is native to arctic tundra of northern Canada, Greenland and Alaska and northern Eurasia.
- Netleaf willow (Salix reticulata) is native to the colder parts of Northern Europe, North America, and Northern Asia.
- Pennsylvania cinquefoil (Potentilla pensylvanica) is native to much of northern and western North America.
- Quaking aspen (Populus fremuloides) is native to North America.
Significant Zone One Region in Siberian Russia
In mountainous northeastern Russia, east of the Central Siberian Plateau is a large area of Zone One plant hardiness represented by Verkoyansk and Yakutsk. As pointed out by the MBG, the Russians, as in the Canadian context, categorize parts of this area as Zone Zero.
Native Plants Thrive in Low Temperatures
The low temperatures experienced in Zone One demand gardeners carefully consider what plants work best in their zone, with a preference for native plants that can not only survive, but thrive.