How To Overwinter Geraniums In Wisconsin

Successfully overwintering geraniums in Wisconsin requires understanding their needs and adapting methods to the state's specific climate. With proper care, these vibrant plants can be preserved from year to year.

Preparing Geraniums for Overwintering

Before the first frost threatens, begin preparing your geraniums for their dormancy period. This involves several crucial steps:

Timing the Transition

Closely monitor weather forecasts. Bring geraniums indoors before temperatures consistently drop below 40°F (4°C). Freezing temperatures can damage or kill the plants.

Pruning and Cleaning

Prune back the geraniums significantly. Remove about one-third to one-half of the plant's growth. This reduces the plant's needs during dormancy and encourages bushier growth in the spring.

Remove any dead or yellowing leaves, spent flowers, and debris from the soil surface. This reduces the risk of fungal diseases and pests during the overwintering period.

Inspecting for Pests

Carefully inspect the geraniums for pests such as aphids, whiteflies, or spider mites. Treat any infestations with insecticidal soap or other appropriate treatments before bringing the plants indoors. Repeat treatments may be necessary.

Overwintering Methods

Several methods can be used to overwinter geraniums, each with its own advantages. The choice depends on your resources and preferences.

Method 1: Bare Root Storage

This method involves storing the dormant geraniums without soil. It requires minimal space but needs careful monitoring.

1. Remove the geranium from its pot.
2. Gently shake off as much soil as possible from the roots.
3. Wrap the roots in newspaper, burlap, or peat moss.
4. Store the wrapped plants in a cool, dark, and dry place, such as a basement or garage where the temperature remains between 40°F (4°C) and 50°F (10°C).
5. Check the roots periodically throughout the winter. Moisten the wrapping slightly if they appear shriveled, but avoid overwatering.

Method 2: Dormant in Soil

This method keeps the geraniums in their pots with soil but induces dormancy through reduced watering and light.

1. Place the potted geraniums in a cool, dark location, similar to bare root storage.
2. Water sparingly, only enough to prevent the soil from completely drying out. Overwatering can lead to root rot.
3. Do not fertilize the plants during dormancy.

Method 3: Growing as a Houseplant

This method involves treating the geraniums as houseplants during the winter. It requires more care but allows for continued growth.

1. Place the potted geraniums in a sunny location, such as a south-facing window.
2. Water regularly, allowing the soil to dry slightly between waterings.
3. Fertilize lightly every 4-6 weeks with a balanced fertilizer.
4. Pinch back the stems regularly to encourage bushier growth.

Caring for Overwintered Geraniums

Regardless of the method chosen, monitoring the plants during the winter is crucial. Adjust care as needed based on their condition.

Monitoring for Problems

Regularly inspect the geraniums for signs of pests, diseases, or dehydration. Address any issues promptly to prevent them from worsening.

Mold Growth: If mold appears on the soil surface, scrape it off and allow the soil to dry out more between waterings. Improve air circulation around the plants.

Pest Infestations: Treat any pest infestations with appropriate insecticides or insecticidal soap. Isolate infested plants to prevent the spread of pests to other plants.

Dehydration: If the plants show signs of wilting or shriveling, increase watering frequency. However, avoid overwatering, which can lead to root rot.

Transitioning Back Outdoors

As spring approaches, gradually acclimate the overwintered geraniums to outdoor conditions before planting them back in the garden. This process hardens them off, reducing transplant shock.

Starting the Transition

Begin the transition process several weeks before the last expected frost. Move the geraniums to a slightly warmer location with brighter light.

Gradual Acclimation

Gradually expose the geraniums to outdoor conditions over a period of 7-10 days.

1. On the first day, place the plants outdoors in a sheltered location for only an hour or two.
2. Gradually increase the amount of time the plants spend outdoors each day.
3. Protect the plants from strong winds and direct sunlight during the initial acclimation period.
4. Bring the plants indoors if frost is predicted.

Repotting (if Necessary)

Before planting the geraniums back in the garden, repot them if necessary. Use fresh potting soil and choose a pot that is slightly larger than the previous one.

Planting Outdoors

Once the risk of frost has passed and the plants have been fully acclimated, plant them back in the garden in a sunny location with well-drained soil.

Additional Tips for Success

• Choose Healthy Plants: Start with healthy, disease-free plants.
• Provide Adequate Light: Ensure geraniums receive sufficient sunlight, especially when growing as houseplants.
• Water Appropriately: Avoid overwatering, which can lead to root rot.
• Fertilize Regularly: Fertilize geraniums regularly during the growing season to promote healthy growth and abundant blooms.
• Monitor for Pests and Diseases: Regularly inspect plants for signs of pests or diseases and take action promptly.

Overwintering geraniums in Wisconsin requires some effort, but the reward of enjoying these beautiful plants year after year is well worth it. By following these steps, even novice gardeners can successfully preserve their geraniums through the harsh Wisconsin winters.

Note: Specific care requirements may vary depending on the variety of geranium. Always observe your plants and adjust care as needed to ensure their health and vigor.