Can Geraniums Survive 35 Degrees

If you’re a gardener, you’ve probably wondered, can geraniums survive 35 degrees? This is a critical temperature point for these popular plants. The short answer is maybe, but it’s risky. Geraniums are not truly hardy in cold weather, and a sudden drop to 35°F can cause damage. Understanding their limits and how to protect them is key to keeping them alive through chilly nights and seasons.

This specific temperature is a real danger zone. While some geraniums can handle a very light frost, 35 degrees Fahrenheit is often the threshold where tissue damage begins. At this temperature, the water inside the plant’s cells can start to freeze. This forms ice crystals that rupture the cell walls, leading to the blackened, mushy leaves you might see after a cold snap. It’s not an instant death sentence, but repeated exposure or a longer duration will certainly harm or kill the plant.

Hardy vs. Tender: Knowing Your Geranium Type

First, it’s crucial to know that “geranium” refers to two main groups. Their cold tolerance varies dramatically.

Pelargoniums (Common Garden Geraniums): These are the colorful annuals you see in pots and beds. They are tender perennials, meaning they are not hardy in cold weather. They thrive in warmth and begin to suffer below 45°F. A night at 35°F is a significant threat.
True Hardy Geraniums (Cranesbills): These are perennial plants, often with looser growth and smaller flowers. Many species are remarkably cold-hardy, surviving winters well below freezing. They are a completely different plant for garden purposes.

When most people ask about surviving cold, they are refering to pelargoniums. The rest of this article focuses on protecting these tender types.

Signs Your Geranium Has Been Cold Damaged

After a cold night, check your plants early. Look for these symptoms:

Wilting or drooping leaves and stems.
Leaves turning dark, almost black, or a translucent brown.
Mushy or water-soaked patches on the foliage.
New growth appearing shriveled or dead.

If you see damage, don’t prune immediately. Wait for warmer daytime temperatures to assess the full extent. Sometimes, the roots and main stems are okay even if the leaves are lost.

Step-by-Step: Protecting Geraniums at 35°F and Below

When the forecast calls for lows near 35 degrees, take action. Here’s what to do:

Bring Potted Geraniums Indoors: This is the simplest solution. Move pots to a garage, shed, basement, or even a sheltered porch. They don’t need light for a night or two.
Cover In-Ground Plants: Use frost cloth, old bedsheets, burlap, or even cardboard boxes. Avoid plastic directly on the foliage, as it can transfer cold. Drape the cover over the plant and secure it to the ground to trap heat from the soil.
Water the Soil: Damp soil retains heat better than dry soil. Water the base of your plants during the day before the freeze arrives.
Add Mulch for Root Insulation: A thick layer of mulch around the base of in-ground plants helps protect the roots from temperature swings.
Use Heat Sources: For valuable plants, you can place outdoor-safe heat lamps or even holiday string lights (not LEDs, as they don’t produce heat) under the cover. Always prioritize safety with electrical items outdoors.

Long-Term Winter Survival Strategies

If you live in a climate with sustained cold, keeping geraniums alive requires more planning. They cannot stay outside. Here are three common methods:

Overwintering as Dormant Plants

This is a space-saving method. Before the first hard frost, dig up the plants. Shake off excess soil, prune them back by about half, and let them dry for a day. Then, hang them upside down or place them in paper bags in a cool (45-50°F), dark place like a basement. Check monthly and soak the roots in water for an hour if they are shriveled. In spring, pot them up and water well.

Overwintering as Houseplants

Bring your potted geraniums inside to a sunny window. They will likely grow leggy with less light, but you can keep them alive. Cut them back by a third, check thoroughly for pests, and water sparingly over winter since they won’t be actively growing much. A south-facing window is ideal.

Taking Cuttings

Sometimes the best approach is to start fresh. In late summer, take 4-6 inch stem cuttings. Remove the lower leaves and dip the end in rooting hormone. Plant them in a moist potting mix. Once rooted, keep these small, manageable plants on a sunny indoor windowsill through winter. You’ll have vigorous new plants for spring.

What to Do After a Frost or Freeze

If you were caught off guard, don’t panic. Follow these steps:

Wait for the Thaw: Let the plant naturally warm up with the morning sun. Don’t touch frozen foliage, as it’s brittle.
Assess the Damage: Once thawed, gently squeeze stems. If they are firm, there’s hope. If they are soft and mushy, that part is dead.
Prune Carefully: Using clean pruners, cut back the damaged, soft growth to healthy, firm tissue. Don’t prune into completely green, healthy wood yet.
Resume Normal Care: Place the plant in a sheltered, bright location and resume careful watering. Be patient; new growth may take several weeks to appear from the buds.

FAQ: Geraniums and Cold Weather

Q: What is the lowest temperature geraniums can tolerate?
A: Tender pelargonium geraniums can often survive a very brief, light frost down to about 32°F, but it’s not guaranteed. Sustained temperatures below 40°F will stunt growth and cause damage. They are not hardy in cold weather for the long term.

Q: Can geraniums come back after a freeze?
A> It depends on the severity. If only the leaves are damaged but the stems and roots are alive, they can regrow. If the main stems and roots froze solid, the plant likely will not recover.

Q: Should I bring geraniums inside at 40 degrees?
A> While 40°F won’t kill them, it’s a good precaution. Bringing them in or covering them at this temperature prevents chill stress, which can cause red leaves and halted growth. It’s better to be safe.

Q: Are some geraniums more cold tolerant?
A: Yes, among common pelargoniums, the ivy-leaf and regal types are slightly more sensitive. Zonal geraniums are often a bit tougher. But none are truly hardy compared to true perennial cranesbill geraniums.

Q: How do I know if my geranium is dead or dormant after winter?
A> Scratch the bark on a main stem with your fingernail. If you see green underneath, it’s alive. If it’s brown and dry all the way through, that stem is dead. Check several spots, including at the base near the soil.

Preparing Geraniums for Cooler Fall Weather

As summer ends, start acclimating your plants. This helps them toughen up slightly.

Reduce watering gradually to slow growth.
Stop fertilizing by late summer so new, tender growth isn’t stimulated just before cold arrives.
Begin moving potted plants to slightly sheltered locations to get them used to less intense conditions before bringing them fully indoors.

Planning ahead is the best defence against a suprise cold snap. Keep an eye on the autumn forecast and have your covers or indoor space ready. With the right care, you can enjoy your favorite geraniums for many years, even if they aren’t hardy in cold weather. Their vibrant color is worth the little extra effort to protect them.