According to the USDA Merrill is in USDA Zone 4a. Here is some general info for USDA Zone 4a to help you get started.
| Average Date of Last Frost (spring) | May 15 |
| Average Date of First Frost (fall) | September 15 |
| Lowest Expected Low | -30°F |
| Highest Expected Low | -25°F |
This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.
You can view the USDA Zone map for Wisconsin here:
Below is a list of planting guides for Merrill, WI. These guides are based on data from Zone 4a.
Vegetables
Herbs
Flowers