It’s no surprise that there are over 300 clematis varieties brightening up gardens all over the globe. These climbing beauties come in just about every color and size imaginable, but they also vary wildly in their hardiness. From evergreen types to delicate varieties that can’t stand a frost, knowing how to care for your clematis during the off-season is key to a successful spring bloom.
A Quick Temperature Guide
While tropical and subtropical clematis species are stunning, they don’t usually make much sense for most North American gardens unless you’re in a very warm zone. For those of us dealing with real winters, here are the varieties commonly planted and the minimum temperatures they can typically handle:
- Traveler’s Joy (Clematis vitalba): down to -35°F
- Italian Clematis (Clematis viticella): down to -13°F
- Herbaceous Clematis (Clematis integrifolia, Clematis recta): down to -13°F
- Alpine Clematis (Clematis alpina): down to -13°F
- Anemone Clematis (Clematis montana): down to -4°F
- Chinese Clematis (Clematis kweichowensis): down to 10°F
- Passion Flower Clematis (Clematis florida): down to 10°F
If you’ve got one of the hardier varieties on this list, you generally won’t need to worry about any extra winter protection.
Caring for Non-Hardy Varieties
If you’ve fallen in love with a variety that’s sensitive to frost, your best bet is to plant it in a container. Once the thermometer starts dipping below 23°F (-5°C), it’s time to move your pot to a frost-free spot. A cool garage or basement between 40°F and 60°F is the “sweet spot” for overwintering. During this dormant phase (usually September through March), cut back on watering and stop fertilizing entirely.
Outdoor Protection Tips
Even if you live in a region with relatively mild winters, it’s a smart move to give your plants a little “blanket.” Covering the root zone with a thick layer of mulch, fallen leaves, or brush can provide a nice buffer against temperature swings. This is also a great “insurance policy” for your hardier varieties if a record-breaking cold snap happens to head your way!
