What Temperatures Can Geraniums Tolerate? A Guide to Caring for These Beautiful Flowers

Geraniums are a well-known flower for their lovely scent and bright, colorful blooms. These pretty plants will make any garden, patio, or balcony look better. But like any plant, geraniums have optimal temperature requirements. You can keep geraniums growing well outside if you know what temperatures they can handle.

Understanding Geraniums’ Temperature Needs

Geraniums prefer consistent, moderate temperatures between 55-75°F (13-24°C). Geraniums can be stressed when temperatures drop below freezing or rise too high, which can cause them to not grow well or bloom well. Different types and species of geranium can handle a range of temperatures, but most do best in this area.

It’s especially important to understand geraniums’ minimum and maximum temperature thresholds Let’s take a closer look

Minimum Temperature for Geraniums

Geraniums can handle temperatures as low as 40 to 50°F (4 to 10°C), but growth slows down a lot below 50°F. Flowers and leaves can be damaged by being exposed to temperatures at or below 40°F for a long time. Frost is especially hazardous, potentially killing the entire plant.

To help geraniums survive colder temperatures:

• Move potted geraniums to a protected spot, like an unheated garage or porch.
• Cover in-ground plantings with mulch, leaves, or another insulating material.
• Erect temporary barriers to block wind, which worsens cold damage.
• Water thoroughly before a freeze; moist soil retains more heat.

Choose cold-tolerant ivy and zonals if colder nights are common in your area. Move pots indoors when temperatures drop below 40°F.

Maximum Temperature for Geraniums

While geraniums tolerate heat reasonably well, temperatures above 90°F (32°C) can cause stress, wilting, and leaf scorch. For best growth and flowering, aim to keep geraniums below 85°F (29°C).

To help geraniums cope with heat

• Move pots to a shadier spot or partially cover with shade cloth.
• Water frequently and deeply to keep soil evenly moist.
• Mist leaves to boost humidity around plants.
• Switch to heat-loving varieties like ivy geraniums.

Temperatures exceeding 100°F (38°C) can severely damage geraniums. Move pots into an air-conditioned space when possible during extreme heat.

How Quickly Do Geraniums Adapt to Temperature Changes?

Geraniums can adjust to gradual temperature swings over one to two weeks. Their resilience depends on the rate of change and extreme high and low temperatures reached.

Ivy and zonals adapt most readily to varying temperatures. Martha Washington and regal geraniums prefer more stable conditions. Still, even finicky regals can acclimate successfully if temperature changes are introduced gradually.

Monitor geraniums closely when moving them to different conditions. Look for these signs of temperature stress:

• Wilting or drooping leaves and flowers
• Yellowed, browned, or curled foliage
• Sparse blossoms and new growth
• Leaf drop or dieback of stems and shoots

If you see stress signals, temper the temperature change by moving plants to a transitional area. For example, a partly shaded porch can help indoor geraniums harden off before moving outside. With time and care, geraniums can adapt to quite diverse temperatures.

Other Environmental Factors Affecting Geraniums’ Temperature Tolerance

Several key environmental factors impact how well geraniums tolerate temperature changes:

Light – Too much hot sun exacerbates heat damage, while insufficient sunlight weakens plants and reduces cold resilience.

Soil moisture – Extremes of too wet or too dry impede geraniums’ ability to handle temperature swings.

Humidity – Misting plants helps boost moisture when moving geraniums into drier or hotter conditions.

Air circulation – Good airflow is important but avoid drafts which intensify cold damage.

Soil quality – Rich, well-draining soil gives geraniums resources to cope with new temperatures.

Wind protection – Block cold winds which greatly amplify winter chill.

Monitor these factors closely when changing geraniums’ growing conditions. Adjust care as needed to help temper the effects of new temperatures.

Choosing Temperature-Tolerant Geranium Varieties

Hundreds of geranium varieties exist, and some tolerate temperature extremes better than others. Choosing resilient types for your climate can boost success.

Ivy geraniums – Very cold hardy, down to 20°F (-7°C). Tolerates hot and dry conditions.

Zonal geraniums – Withstands cold to 20°F (-7°C) and heat to 90°F (32°C). A tough, adaptable type.

Martha Washington geraniums – Survives cold as low as 10°F (-12°C) and heat to 90°F (32°C).

Regals – The least cold-hardy, but their showy blooms compensate. Prefers cool conditions.

Check tags and descriptions carefully when purchasing geraniums to select variations suited for your local climate. With the right choices and care, geraniums can thrive through seasonal shifts in temperatures.

Understanding geraniums’ ideal temperature range allows you to site and care for them appropriately. Follow these core tips to help your geraniums tolerate diverse temperatures:

• Choose cold and heat-hardy varieties like ivy and zonal geraniums.

• Introduce temperature changes slowly over one to two weeks.

• Provide supplemental care like shade, humidity, and wind protection.

• Watch for signals of stress and modify conditions accordingly.

• Keep soil moist but well-drained in temperature extremes.

Taking some simple precautions will allow you to enjoy geraniums despite unpredictable seasonal swings. Pay heed to their temperature limits, and your geraniums will reward you with endless flowers and beauty.