Coral Bells Cold Tolerance Explained

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Coral bells are evergreen, low-maintenance perennial plants that can withstand many harsh conditions, such as drought and cold. However, exposure to either extreme can damage the plant. So, how much cold can coral bells tolerate?

During winter, coral bells can tolerate temperatures of up to -25 degrees Fahrenheit (-31 degrees Celsius) when dormant and 40 degrees Fahrenheit (4.4 degrees Celsius) when active. However, to survive these low temperatures, you must plant them in light and well-draining soils.

The rest of this article will give more insight into this topic. First, I will discuss how cold-hardy coral bells are and give you some valuable tips for preparing the plants for winter. I will also highlight the effects of exposing your heuchera plant to too much cold.

How Cold-Hardy Are Coral Bells?

Heuchera (coral bells) are considered hardy in USDA zones 3 through 8 (source).

This plant can withstand temperatures as low as -25 degrees Fahrenheit (-31 degrees Celsius). However, despite surviving such low temperatures, you may notice that the coral bells have gone into dormancy or started displaying brown, wilting top leaves.

Furthermore, potted coral bells have less tolerance for cold than those grown in a garden. For instance, they can only survive temperatures as low as -5 degrees Fahrenheit (-20 degrees Celsius) (source). 

How To Care for Your Coral Bells During Winter

Although coral bells are considered cold-hardy, it would be best if you prepared your plants to survive the cold winter season better. Winterizing coral bells should be done in late fall before freezing temperatures set in.

The biggest threats to your plants during winter are frost damage and root rot. Fortunately, with proper controls, you can mitigate these risks.

Here are some tips to guide you:

• Use well-draining soils to prevent fungal growth and root rot due to water saturation at the plant roots.
• Improve soil drainage by adding 2 to 4 inches (5.1 to 10.2 centimeters) of organic matter.
• Apply a layer of mulch over the soil to prevent frost heaving (source). Mulching also helps by insulating the soil to retain some much-needed heat. A mulch cover also protects the plant’s shallow roots from frost damage. 
• Reduce the frequency of watering your coral bells, and only irrigate when the soil is dry.
• Water the coral bells in late fall, as this helps them tolerate the cold better and retain heat.
• Cut back any damaged plant parts since they are more susceptible to frost damage.
• Prune the plant to about 3 inches (8 centimeters) for colder areas.
• Do not apply any fertilizers, as coral bells do not take well to them (the compost layer you add will supplement the soil’s nutrient deficiencies).

Potted coral bells may not do as well as those growing in the garden during winter. Furthermore, coral bells do not thrive when planted indoors. Opt to plant them in an outdoor garden for best results through all seasons.

How Overexposure To Cold Temperatures Affects Coral Bells

As mentioned earlier, coral bells can survive in temperatures as low as -25 degrees Fahrenheit (-31 degrees Celsius) when dormant and 40 degrees Fahrenheit (4.4 degrees Celsius) when active. However, when the temperatures drop, the plant may exhibit signs of frost damage and, in severe cases, completely die off.

Similarly, not winterizing your plants correctly can expose them to frost damage and potential death.

Frost damage in plants occurs when ice crystals form within plant tissue, interfering with essential processes and causing damage. The most vulnerable parts are usually older or damaged leaves since other factors like pests and diseases may already compromise them. 

New growth may also be affected since the leaves have not developed enough to withstand the extreme cold.

How can you tell if your plants have been overexposed to cold temperatures? Here are some signs to guide you:

• Wilted leaves
• Darkening or browning leaves
• Leaves becoming dry and crispy
• Plant death

Unfortunately, frost damage cannot be reversed. If the plant has not been completely damaged, new shoots can grow and give new life to the plant. However, the plant is unlikely to recover in severe cases where more than half of the roots have suffered tissue damage.

Moreover, frost-damaged plants may not flower during flowering seasons.

How To Handle a Frost-Damaged Coral Bell

When you discover a frost-damaged coral bell, please resist the urge to cut off the affected plant parts because it may inadvertently cause further damage. Moreover, the dead leaves provide additional insulation to the plant and help it withstand freezing temperatures better.

You must wait for a period of 45 days from the start of winter to remove any frost-damaged parts from your coral bells.

Preventing Frost Damage in Coral Bells

Follow the recommended winterization procedure to protect your coral bells from frost damage (as highlighted previously). 

In addition, you can prevent frost damage to your plants by covering them with a frost blanket. A frost blanket is an excellent investment for keeping the younger plants safe from frost damage. I recommend the Valibe Blanket Plant Cover (link to Amazon), because of the following benefits:

• It offers protection from plant pests too
• It is made from a lightweight and breathable material, which is excellent because coral bells need adequate airflow to thrive
• Provides insulation for your coral bells
• It is multipurpose and can be reused on other plants in your garden

Conclusion

Coral bells are cold-hardy plants that survive cold winters by going into dormancy. This means that though they are alive, they do not grow any further. Nonetheless, these plants can succumb to frost damage if not properly winterized.

Caring for coral bells during winter primarily involves protecting them from root rot and frostbite. Root rot can be prevented by reducing the watering frequency and only irrigating when the soil dries.

On the other hand, frostbite can be controlled by integrating proper winterization procedures and using a frost blanket. 

Unfortunately, plant parts affected by frost damage cannot be revived.