Hey, cutie, what's your zone? Pick up line? Naw, just garden center conversation starter. If someone were to use that line on me, how would I respond? With indecision, that's how.
If I could zoom in far enough on the USDA map, maybe I could tell whether they say I'm in Zone 7a or 6b, but I can't find a site that will allow me to zoom in closer than the entire mid-Atlantic region. Pretty useless, really. HGTV says I'm Zone 7a. The Arbor Day Foundation and the American Horticultural Society say I'm squarely in the middle of Zone 7. Better Homes and Gardens puts me in Zone 6b with Zone 4b located just a few miles away to the west and 9a a few miles to the east. What happened to Zones 5, 7 and 8? I'd love to know where that imaginary line is that takes me magically from Zone 6b into 4b or 9a. Would I see different plants? Would the plants respect that line (snicker, snort)? I guess the BHG is a map you can afford to disregard.
Aw, heck. Does it matter? Yes, it does. I gardened for more than 10 years here in Maryland thinking I was in Zone 6. Then I "discovered" I might be in Zone 7. Did it change the plants I was using? No. Did I lose a single plant because I thought I was in a zone I really wasn't in? No. Did I lose plants because I didn't take care of them properly? Let's not go there. I want to chalk those situations up to learning experiences; after all, experience is the best teacher, and may their little plant souls rest in peace. But, if I'd planted a plant with a Zone 8-10 range here where I live, I'm pretty sure it would not be around right now. Same for plants that require cooler climates than my Zone 6b, or Zone 7 or wherever I am, can provide. I was always told we couldn't grow Rosemary and Lavender outside over the winter here. Hello. I had Lavender bushes with trunks (yes, trunks) over two inches in diameter. The Rosemary would have been as substantial if big air conditioning guy hadn't planted his 300+ pound feet on top of it multiple times. But it didn't die. True, these plants were in a south-facing ell created by my house and garage, but thrive they did.
This past Sunday, Paul James, The Gardener Guy of Gardening by the Yard on HGTV, had a piece on climate zones. One thing he emphasized was microclimates. While you likely won't be able to cross more than a zone, you can be in Zone 6b and create a Zone 7 or 7b microclimate by planting things in a sheltered spot, such as against a masonry wall in a south facing location. I'm pretty sure I created a microclimate for the Lavender and Rosemary. I'm also sure I created a microclimate much too warm for my doublefile viburnum when I attempted to espalier it against a cream-colored vinyl siding wall that faced south. Poor thing started looking burned even in late spring. By mid summer, no matter how much I watered it, the leaves were shriveled and starting to drop. When I moved it 40 feet away from the house into a slightly shady area, it took off and obviously forgave me for trying to fry it. So, with plants, just like real estate, location is everything. Sometimes just a few feet can make a huge difference.
While climate zones matter, you may be able to grow things not ideally suited to your zone by creating microclimates. It may take a little extra work on your part, but if it's a plant you love and just have to have, it may be worth the effort.