Pansies are among the most popular and versatile flowers, known for their vibrant colors and charming “faces.” These cool-weather favorites are perfect for adding a splash of color to gardens when many other plants aren’t in bloom. But before planting, it’s important to know the pansy temperature tolerance and what temperature will kill pansies.

Pansy Temperature Tolerance Range

Known for their resilience in cool temperatures, pansies make an excellent choice for fall, winter, and early spring planting in many regions.

But What Temperature Will Kill Pansies?

Cold Temperatures:

1. Frost Tolerance: Pansies are equipped to handle light to moderate frost. Their foliage is robust, and while the flowers are more delicate, they can typically endure temperatures dropping to around 28°F (-2°C) without significant damage.
2. Freezing Temperatures: Extended exposure to freezing or deep frost, particularly in the 25°F (-4°C) range and below, can damage the flowers. If the temperature dips between 15°F and 20°F (-9°C to -6°C), the blooms are likely to suffer, but the plant might endure.
3. Extreme Cold: Consistent extremely cold temperatures, especially below 15°F (-9°C), can threaten pansies, possibly resulting in their death. Pansies in containers are more vulnerable during cold spells since the soil can freeze solid, endangering the roots.

Hot Temperatures:

1. Mild Heat: Pansies prefer cooler temperatures, and while they can tolerate mild warmth, they start to show stress when the mercury rises consistently above 70°F (21°C).
2. Extreme Heat: Prolonged periods in temperatures above 75°F (24°C) can be problematic. Pansies tend to become leggy, their bloom production may slow down or stop, and they may show signs of wilting or sunburn.

Protecting Pansies from Temperature Extremes

Cold Protection:

• Mulching: A generous layer of mulch around pansies can insulate the soil, offering protection to the roots.
• Covering: On frosty nights, cover pansies with frost cloths, old bed sheets, or burlap. Make sure to remove these covers during daytime to allow the plants to access sunlight.
• Watering: Ensure the soil is moist (but not drenched) before a frost. Moist soil holds heat better than dry soil, providing some frost protection.

Heat Protection:

• Shade: During heatwaves, consider providing temporary shade for your pansies. Shade cloth, an umbrella, or even strategically placed garden furniture can shield them from intense midday sun.
• Watering: Keep the soil consistently moist but avoid waterlogging. Early morning watering is ideal, as it prepares the plant for the day’s heat and reduces the chances of fungal diseases that can occur with evening watering.

Are Pansies Perennials or Annuals?

Pansies are actually biennial but it depends on several factors. For more on this check out our article titled: Are Pansies Perennials?

Will Pansies Survive Winter in Pots?

Pansies are known for their frost tolerance, but surviving winter in pots presents unique challenges compared to in-ground plantings. Potted plants are more exposed and therefore more susceptible to extreme temperature fluctuations.

Here’s what you need to know if you want to try overwintering pansies in pots:

Factors Affecting Winter Survival in Pots

1. Hardiness Zone: In zones 7 and above, pansies have a higher chance of surviving the winter in pots. In colder zones, the chances diminish significantly unless you take special precautions, such as some of the following factors and tips below that.
2. Pot Material: Pots made from insulating materials like wood or thick plastic are better at protecting the root system than thin or porous materials like clay.
3. Pot Size: Larger pots have more soil and therefore offer better insulation for the root system. Small pots can freeze through more quickly.
4. Location: Place the pots against a building wall or in a sheltered area to protect them from wind, which can exacerbate the effects of cold temperatures.

Tips for Overwintering Pansies in Pots:

1. Insulate the Pot: You can insulate the pot itself by wrapping it in burlap or bubble wrap, or by burying it in a pile of straw or leaves.
2. Mulch the Soil: Adding a thick layer of mulch to the top of the soil can provide additional insulation and help retain moisture.
3. Watering: Soil in pots dries out more quickly, even in winter. Make sure to water the pansies, but avoid overwatering, as excessively wet soil can lead to root rot.
4. Cover During Extreme Cold: If a particularly harsh cold snap is forecasted, consider covering the potted pansies with frost cloth or moving the pots to an unheated garage or shed.
5. Indoor Storage: For those in particularly cold climates (zones 1-6), bringing the potted pansies indoors during the harshest winter months is an option. However, it’s important to keep them in a cool and well-lit area, like a sunroom that isn’t heated, to simulate winter dormancy.
6. Check for Pests: Before bringing any plant indoors for winter, it’s a good idea to check for pests like aphids or spider mites and treat if necessary.
7. Periodic Checks: Throughout the winter, continue to check the soil moisture and overall plant health. Pansies are dormant during this period but still require basic care.

While it’s possible for pansies to survive winter in pots, especially in milder climates, it does require some extra attention to detail. With proper care and a bit of luck, your potted pansies could not only survive but thrive and bloom again come spring.

The Importance of Timing

Whether you choose to plant in the fall or spring, timing is essential. Planting too early in hot weather or too late into a cold season can stress the plants and reduce blooming. Always pay attention to local weather forecasts and adjust your planting schedule accordingly.

Here you can find information on when to plant pansies by zones and states, and also info on whether pansies are perennials, annuals or biennials.

Summary

Pansies are a wonderful addition to any garden due to their hardiness and bright colors. Knowing when to plant them in your specific hardiness zone can greatly improve your chances of enjoying a lush and colorful display. Whether you opt for fall or spring planting (or both!), proper soil preparation and timely planting are key to growing beautiful pansies.

Happy gardening!