Here is some general info for USDA zone 4b to help you get started.
|Average Date of Last Frost (spring)||May 15|
|Average Date of First Frost (fall)||September 15|
|Lowest Expected Low||-25°F|
|Highest Expected Low||-20°F|
This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.
Below is a list of planting guides for Zone 4b.