"My perennials never seem to make it through the winter.
Do I have a black thumb instead of a green one?"
|Stop and smell|
There is no such thing as a black thumb - you're just choosing the wrong plants for your zone.
There are zone maps in garden centers everywhere so it's easy to find the planting zone for your garden. You can also check with your local university extension office - even Google a planting zone map.
Once you find your zone, determine the actual temperature of your specific garden.
For example, here at Cheesecake Farms in Virginia, our planting zone (according to the regional map) is zone 7. This means that our winter temperature doesn't dip below zero.
So, even though we're technically in zone 7, our gardening area is more like zone 6 where temperatures can go as low as minus 10 degrees.