What Temperature Can Impatiens Tolerate? A Guide to Growing Impatiens in Cold Weather

With their colorful blooms in shades of red, pink, white, purple, and more, impatiens are a popular choice for adding a pop of color to shady garden beds and containers However, these flowering annuals are native to tropical climates and are extremely sensitive to cold temperatures. If you’re new to growing impatiens, it’s important to understand their ideal temperature range and how to protect them from frost damage

An Overview of Impatiens and Cold Tolerance

There are over 1.000 species in the Impatiens genus but two types are most commonly grown

• Standard impatiens (Impatiens walleriana) – These impatiens produce single or double flowers on stems that grow 1-2 feet tall They are prone to downy mildew disease

• New Guinea impatiens (Impatiens hawkeri) – A hybrid species with larger, more colorful blooms on robust 2-3 foot tall plants. Generally less susceptible to disease.

Both standard and New Guinea impatiens are native to tropical climates and cannot tolerate any frost or freezing temperatures. Their thin, succulent stems and leaves will quickly blacken and die when exposed to temperatures below 35°F (2°C). Even a brief overnight freeze can kill the entire plant.

Let’s explore impatiens’ ideal temperature range and how to help them survive inevitable cold snaps.

What Exactly is Considered a “Frost-Free” Climate for Impatiens?

Impatiens should not be exposed to frost or freezing conditions at any point. But what does this mean in terms of an actual temperature range?

Ideally, temperatures should not drop below 40°F (4°C) for the healthiest impatiens plants. They enter dormancy below 50°F (10°C) to conserve energy.

Brief exposure to the high 30s may be survived if the plant is mature and healthy. However, temperatures below 35°F (2°C) can damage and potentially kill unprotected plants.

So for best results, impatiens should be grown in areas that do not experience frost or freezes during their active growing season.

Tips to Grow Impatiens Successfully in Cool Climates

Even if you live in a zone with cold winters, you can still enjoy growing impatiens during the frost-free months by following these tips:

• Wait until after the last spring frost to plant. This varies by region, but make sure overnight lows stay above 40°F before setting out impatiens.

• Provide afternoon shade. Dappled sunlight is ideal to prevent excess heat stress.

• Water frequently. Impatiens like consistently moist soil. Multiply watering in hot, dry periods.

• Use cold tolerant varieties. Some newer impatiens cultivars are bred to better handle cooler temps.

• Grow in containers. Pots can be moved indoors or to sheltered areas as needed.

• Protect from early fall frosts. Cover or move pots indoors if frost threatens at the end of the growing season.

• Mulch the ground around plants. This insulates roots and reduces frost heaves.

• Provide wind protection. Use shrubs or fences to block chilling winds.

How to Tell if Impatiens Have Been Damaged by the Cold

It doesn’t take much exposure to freezing temperatures for impatiens to show signs of distress:

• Leaves turn black or translucent

• Stems and leaves become limp, wilted, and mushy

• Flowers quickly shrivel and die

• Entire plant collapses into a blackened mess

If you see these symptoms, the impatiens have likely experienced irreparable frost damage. Any parts that still look green may recover, but the plant will likely be disfigured or weakened. It’s best to remove and discard the damaged parts.

Protecting Impatiens from Early and Late Season Frosts

While impatiens cannot survive being frozen, you can take steps to protect them from light frosts:

• Cover with fabric row cover or garden fleece. Anchor the edges with rocks or landscape staples to trap ground heat.

• Use cloches or cold frames. Place individual cloches over smaller plants or a cold frame over larger plantings at night.

• Water well before a frost. Moist soil holds more heat than dry soil. Avoid wetting foliage.

• Move pots to a sheltered spot. Place near the house foundation or under an overhang. Stack close together.

• Harvest cut flowers. Cut blooms to enjoy indoors and remove dead flowers to prevent rot.

Knowing When to Bring Impatiens Indoors for the Winter

In areas where heavy frosts and freezes are imminent, plan ahead to overwinter impatiens indoors:

• Transition inside in early fall. Bring pots inside well before the first expected frost, when temperatures are still mild (above 50°F).

• Gradually reduce watering. Slowly let the soil dry out a bit to send the plants into dormancy.

• Provide bright, indirect light. A south-facing window is ideal. Supplement with grow lights.

• Keep temperatures around 60-70°F. Cooler is better to maintain dormancy until spring.

• Cut back and discard dead growth. Keep only healthy stems and leaves.

• Do not fertilize. Impatiens do not actively grow indoors over winter.

The Takeaway: Choose Cold-Tolerant Varieties

The bottom line is that standard impatiens have very little tolerance for frost or freezing weather. But by selecting more cold-hardy varieties and taking protective measures, you can continue enjoying their cheery blooms even in cooler climates. Seek out New Guinea types touted as “cold tolerant” and plant in protected microclimates.

When in doubt, play it safe and wait until nighttime temperatures are reliably above 40°F before setting out these tropical beauties each year. With extra care taken at the beginning and end of the growing season, impatiens can brighten your landscape all season long.