The seventeen species of Bitterroot (or *Lewisia*) originally hail from the rugged mountain ranges of Western North America. You’ll find them stretching all the way from Canada down through the US and into Baja California, Mexico. Because they come from such diverse elevations and regions, different species have adapted to very different climates. This is exactly why some varieties handle a cold winter like a champ, while others might struggle if left out in the elements.
Some Varieties Are Tough as Nails
For certain types of Bitterroot, overwintering outdoors is actually a breeze. Some of these hardy varieties can withstand temperatures as low as -4 degrees Fahrenheit (-20°C). They’ll make it through even a brutal cold snap without breaking a sweat. *Lewisia cotyledon* is a great example of one of these tough cookies. However, keep in mind that Bitterroot isn’t exactly known for being a long-lived plant anyway. Instead of stressing too much about keeping a single plant alive for a decade, your best bet is to focus on propagating your plants to keep the cycle going.
It’s All About the Moisture
When it comes to surviving the winter outside, a sudden drop in temperature is rarely the real “plant killer”—it’s usually the wet soil. Bitterroot is incredibly sensitive to standing water and “wet feet.” Too much moisture leads to root rot, which is a death sentence for the entire plant. To play it safe, it’s often a smart move to dig up your Bitterroot and move it into a pot before the winter rains hit. You can keep the pot in a greenhouse or an unheated sunroom. This way, you have total control over the water and can make sure your plant stays dry and happy.
Young Plants Need Extra Love
If you have a winter-hardy variety in your garden, you still need to keep a close eye on the “babies.” Young plants are much more vulnerable to the elements than established ones. Even if you live in a relatively dry area, it’s usually worth the effort to bring these youngsters indoors before the first frost hits.
To wrap it up, here’s the game plan for Bitterroot in the winter:
- Only specific varieties are truly winter-hardy.
- Excessive rain and moisture are often bigger threats than the cold.
- When in doubt, pot them up and bring them to a sheltered spot for the season.
