In Manitoba in winter time in Winnipeg they always tell people to know your zone or you’ll get towed. I’m not talking about those zones, but hardiness zones. In Canada there are 8 different climate zones with 0 being the coldest and zone 8 being the mildest. Manitoba zones are between 0 to 4. In Winnipeg there might be some micro climates which could be zone 5.
What should you know your hardiness zone? Some plants are perennials and will come come back up year after year. A perennial herb is a plant that will last more than 2 years in your garden. Most of them go dormant over the winter months, to come back again in spring. Not all perennials will survive a zone 3 winter.
Some herbs and flowers that will surive zone 3 are: yarrow, hyssop, catnip, chives, and sorrel. Some herbs and flowers will re reseed: dill, calendula, borage, and cilantro. Zone 4 perennials, which can survive zone 3 if mulched and you’re willing to take a bit of a risk are: some mints, lemon balm, and bee balm.
When buying perennial plants and you want them to survive the winter make sure you know what zone they are hardy too.
Know your zone websites:

Catnip 
Chocolate Mint 
Dill
