Geraniums, typically originating from tropical climates, are known to be fairly hardy plants that can tolerate a range of temperatures. However, when it comes to extreme cold, such as temperatures around 40 degrees Fahrenheit (4 degrees Celsius) and below, geraniums may struggle to survive if left outdoors.
In regions with mild winters, like Los Angeles, where temperatures rarely drop below freezing, it is possible to leave geraniums outside year-round. The average low temperatures in Los Angeles during the winter months range from the mid-40s to low 50s, which falls within the tolerance level of geraniums.
However, it’s important to note that even though geraniums can handle temperatures down to the 40s, they are not frost-tolerant. Frost occurs when temperatures drop to 32 degrees Fahrenheit (0 degrees Celsius) or below, causing ice crystals to form on plant tissues. Geraniums are highly susceptible to frost damage, and exposure to freezing temperatures can quickly lead to blackened and dead foliage.
To protect geraniums from freezing temperatures, it is advisable to bring them indoors or provide some form of winter protection. If you live in an area with occasional cold snaps or frosty nights, you can take several steps to ensure the survival of your geraniums:
1. Move geraniums indoors: Before the first frost, carefully dig up your geraniums from the garden and transplant them into pots. Place them in a sunny location indoors, such as a south-facing window, where they can continue to receive adequate sunlight. Remember to acclimate the plants gradually to the lower light levels indoors to avoid shock.
2. Provide supplemental lighting: If you don’t have suitable sunny windows, you can use artificial grow lights to provide the necessary light for your geraniums. Position the lights about 12-18 inches above the plants and keep them on for 12-14 hours a day to mimic natural daylight.
3. Adjust watering and humidity: Indoor environments tend to be drier than outdoor conditions. Monitor the moisture levels in the soil and water your geraniums only when the top inch of soil feels dry. Avoid overwatering, as it can lead to root rot. Additionally, consider placing a tray filled with water and pebbles near the plants to increase humidity levels.
4. Maintain proper temperature: Geraniums prefer temperatures between 60-75 degrees Fahrenheit (15-24 degrees Celsius). Keep them away from drafts or excessively warm areas, such as near heating vents or radiators, as these can cause stress to the plants.
5. Prune and groom the plants: Remove any damaged or dead foliage to promote healthier growth. You can also pinch back the stems to encourage bushier and more compact growth. Regular grooming will help your geraniums thrive indoors and prepare them for the eventual return to the garden in spring.
6. Consider overwintering in a cool location: If you have a cool, unheated space like a basement or garage that remains above freezing, you can also choose to overwinter your geraniums there. Before moving them, trim the plants back to about half their size, remove any dead leaves, and place them in containers with well-draining soil. Water sparingly during winter dormancy.
7. Monitor for pests and diseases: Indoor environments can sometimes lead to increased pest problems. Regularly inspect your geraniums for pests like aphids, spider mites, or whiteflies. Treat any infestations promptly to prevent damage to the plants.
By taking these precautions and providing the necessary care, you can successfully overwinter your geraniums and protect them from the potential harm of 40-degree weather and frost. However, it’s always advisable to monitor local weather conditions and adjust your plant care accordingly.
