I live in the Catoctin Mtns near Cunningham Falls. I would like to plant a trumpet vine, but am uncertain of our planting zone here. We average 10 degrees colder up here than in the valley. Thanks! Missy Grimes
Frederick County Maryland
Here is a hardiness zone map of Maryland.https://images.search.yahoo.com/images/view;_ylt=A0LEVifqEQtVcZQAEtAnnIlQ;_ylu=X3oDMTB0N25ndmVnBHNlY...
You'll notice that the zones vary by 5 degrees. Simply be conservative when you are purchasing plants and base your choices on plants that are 2 zones hardier than your zone. Many plants are hardy to many zones colder than yours.
Keep in mind that there is some variations in hardiness within one species of plant because some varieties of the plant may be more tender.