Have you ever looked at a plant at the nursery and wondered what the USDA Zone means on the label? It may say something like USDA Zone 3-8. What is that all about? We will go over what it means, and what to look for if you are choosing plants on your own.
The higher the zone number, the less cold tolerant a plant is. Zone 1 is the most cold tolerant, which can take temperatures all the way down to -60 degrees Fahrenheit. Zone 13 is the highest, and plants in this zone cannot go below 60 degrees Fahrenheit without damage.
We are in USDA zone 5. If you want to get very specific, we are in zone 5b. That means that we typically only see temperatures drop to -15 degrees Fahrenheit. However, for plant buying we are in zone 5. That means that healthy plants listed as zone 5 can tolerate temperatures that cold through the winter and survive to see another spring. The closer to Lake Michigan you are, the closer to zone 6 you may be. The relatively warm waters of Lake Michigan help to keep temperatures up through the winter.
Everything we plant is for zone 5. If we design a landscape for you, or suggest just a plant, we make sure that it is hardy enough to survive the winter. Now there are micro-climates where sensitive plants may be able to survive in the landscape through the winter, but I would never count on that. It is very much so the exception, not the rule.
Annuals are typically zone 10 or higher. They will die by the time that temperatures dip below 35 degrees Fahrenheit. So when you plant your marigolds, they are at least zone 10, and that is why they will not tolerate the cold weather.
Next time that you look at a plant at the nursery, you will know what the tag means when it tells you the acceptable zone range. Then you can pick out the best plants to survive in your landscape, something that survives in USDA zone 5. And if we present plants to you, we always take that into account.