The new plant hardiness zone map for Colorado has come out from the
USDA. As we all know, its warmer here in Colorado during the winter, and the maps are finally catching up.
As you can see a good part of the Denver area is now in zone 6a a step warmer than the zone 5 that’s been published for ever. So what does that mean for Colorado gardeners? More plants to choose from! I have a few plants I’m hoping to now grow in my garden. It should be noted a lot of the warmer plants also want nice organic rich well drained, acidic soils. So although we’re warmer it doesn’t mean our clay has magically disappeared.
Plum Daphne — with a beautiful dark purple foliage and a semi-evergreen habit, a daphne like this would be great in the partial shade of my front yard.
Camellia — Camellia’s are what I think of when I imagine the quintessential garden plant. With dainty petals, and nice foliage its worth a try in a bed that’s been well amended and in area sheltered from winter’s dry winds. Our clay soils may be just too alkaline for these guys.
The most interesting part of the map to me is seeing how far zone 6 extends into the Colorado river valley from the West. So the down side is likely to be more fires in the mountains and ever more mountain pine beetle kill. It won’t be stopped anytime soon by the natural defense of a deep freeze during mid-winter, or a freeze in fall or early spring when larvae are vulnerable.