As the colder months approach, gardeners face the challenge of protecting their plants from the freezing temperatures of winter. For many plants, especially perennials, the winter season can be a time of dormancy, but for others, it can be fatal if the right precautions are not taken. Overwintering your plants involves protecting them from harsh conditions, whether by moving them indoors, insulating them in place, or providing extra care to help them survive the season.
What is Overwintering?
Overwintering refers to the process of helping plants survive the winter, particularly those that are not naturally suited to cold climates. Some plants, especially tropical and tender perennials, require extra protection to avoid damage from frost and freezing temperatures. There are a variety of methods to overwinter plants depending on the type of plant, its hardiness, and the conditions in your region.
By overwintering plants, you allow them to enter a period of dormancy or reduced activity, protecting them from the stress of winter and enabling them to regrow in the spring.
Why Overwintering is Important
Plants that are not naturally hardy in cold climates can suffer damage or die if left unprotected during winter. For example, tropical plants, tender perennials, and certain annuals are often unable to withstand freezing temperatures. By overwintering these plants, you preserve their health and avoid the need to replace them every year. Additionally, overwintering allows you to save time and money, as you won’t have to repurchase or replant the same species each spring.
Overwintering can also extend the lifespan of certain annuals by bringing them indoors or protecting them from frost. This process helps gardeners cultivate a more consistent and established garden over time, reducing the need to start from scratch each year.
Determining Which Plants Need Overwintering
Before you begin the process of overwintering, it’s important to identify which plants in your garden are at risk during the winter. Some plants are naturally hardy and can survive freezing temperatures with little or no intervention, while others will need more protection.
Plants That Need Overwintering
- Tender Perennials: These are perennials that may not survive in cold climates. Examples include geraniums, begonias, and dahlias.
- Tropical Plants: Plants like hibiscus, banana trees, and palms are not designed to withstand cold temperatures.
- Bulbs and Tubers: Certain bulbs and tubers, such as gladiolus and canna lilies, must be dug up and stored indoors.
- Annuals You Want to Save: Some gardeners choose to overwinter annuals like impatiens or petunias indoors to save them for the next season.
- Container Plants: Plants that grow in containers can be especially vulnerable to cold, as their roots are more exposed to freezing temperatures.
- Houseplants Moved Outdoors for Summer: If you have houseplants that spent the summer outdoors, they will need to be brought inside before temperatures drop.
Plants That Don’t Need Overwintering
Some plants are hardy enough to survive winter without special protection. These include:
- Hardy perennials (e.g., hostas, peonies, daylilies)
- Cold-hardy shrubs (e.g., boxwood, junipers)
- Native plants suited to your growing zone
To determine whether a plant needs overwintering, consult your plant’s hardiness zone requirements and compare it to your local climate.
Methods of Overwintering Plants
There are several ways to overwinter your plants, depending on the species, your climate, and the space available. Below are some of the most common methods for overwintering various types of plants.
1. Bringing Plants Indoors
One of the easiest ways to overwinter tender plants is by bringing them indoors. This method works well for tropical plants, houseplants that spent the summer outside, and even certain annuals that you want to save for next year.
Steps to Bring Plants Indoors:
- Check for Pests: Before bringing any plant indoors, inspect it for pests or diseases. Wash the plant thoroughly to remove any insects or eggs.
- Acclimate the Plant: If the plant has been outside, gradually acclimate it to indoor conditions by moving it to a shaded spot for a few days, then bringing it inside.
- Choose a Bright Spot: Place the plant in a location where it will receive plenty of sunlight, as the indoor light may not be as intense as outdoor conditions.
- Adjust Watering: Plants typically require less water during winter dormancy. Be careful not to overwater, as plants in pots will not dry out as quickly as they do outdoors.
- Monitor Humidity: Indoor air during winter can be dry, so consider using a humidity tray or misting the plants to keep moisture levels up.
2. Using a Cold Frame or Greenhouse
A cold frame or greenhouse can provide the ideal environment for overwintering plants that need protection from frost but don’t require a full indoor environment. Cold frames are simple, enclosed structures that trap heat from the sun, creating a slightly warmer microclimate for plants. Greenhouses offer more space and often provide more temperature control, making them suitable for larger collections of plants.
Steps for Using a Cold Frame:
- Ventilation: Ensure the cold frame has proper ventilation, as too much heat buildup can harm plants.
- Insulate the Base: You can insulate the base of your cold frame with straw or leaves to provide extra protection against freezing temperatures.
- Water Sparingly: Since plants in a cold frame are not actively growing, they will require less water than during the growing season.
3. Mulching and Protecting in Place
For plants that are hardy but still need some winter protection, mulching can be an effective way to insulate the soil and protect roots from freezing temperatures. Mulching works well for perennials, bulbs, and even some shrubs.
Steps for Mulching:
- Apply a Thick Layer: Spread 2 to 4 inches of mulch (such as straw, leaves, or wood chips) around the base of your plants. Be careful not to pile mulch directly against the stems or trunks, as this can lead to rot.
- Use Burlap or Frost Cloths: For extra protection, wrap sensitive shrubs or perennials with burlap or frost cloth to shield them from harsh winds and frost.
- Check for Gaps: Ensure the mulch covers the root zone completely to prevent freezing.
4. Storing Bulbs and Tubers
Certain bulbs and tubers, such as dahlias, gladiolus, and cannas, need to be dug up and stored indoors to survive the winter. These plants will not survive freezing temperatures if left in the ground.
Steps for Storing Bulbs and Tubers:
- Dig Them Up Before Frost: Carefully dig up the bulbs or tubers after the first light frost but before the ground freezes.
- Remove Excess Soil: Shake off excess soil, but avoid washing them, as moisture can encourage rot.
- Cure the Bulbs: Allow the bulbs or tubers to cure in a dry, cool place for a week to help them harden off.
- Store in a Cool, Dark Place: Store the cured bulbs in a container filled with peat moss, vermiculite, or sawdust, in a cool, dark location (such as a basement or garage) where temperatures stay between 35-50°F.
5. Overwintering Container Plants
Container plants are more vulnerable to cold weather than in-ground plants because their roots are exposed to the elements. To protect them, you can either move the containers indoors, bury them in the ground, or insulate them in place.
Steps for Overwintering Container Plants:
- Move Containers Indoors: For tender plants, move the containers to an indoor location, such as a garage or basement, where they will be protected from freezing.
- Insulate the Pot: Wrap containers with bubble wrap, burlap, or other insulating material to prevent the roots from freezing.
- Group Containers Together: Grouping containers close to each other can help reduce heat loss and provide mutual protection.
Comparison Table: Overwintering Methods
Below is a comparison table to help you determine the best method for overwintering your plants based on plant type and environmental needs.
| Method | Best For | Pros | Cons |
|---|---|---|---|
| Bringing Plants Indoors | Houseplants, tropicals, tender perennials | Protects from frost, easy to monitor indoors | Requires indoor space and proper lighting |
| Cold Frame/Greenhouse | Hardy plants, cool-weather crops | Provides frost protection and light | Requires installation, can overheat |
| Mulching in Place | Hardy perennials, bulbs | Simple, inexpensive | May not be enough for tender plants |
| Storing Bulbs/Tubers | Dahlias, gladiolus, canna lilies | Effective for frost-sensitive bulbs | Requires storage space, labor-intensive |
| Overwintering Containers | Container plants, annuals | Convenient, can be done in place | Roots more exposed to cold, needs insulation |
Caring for Houseplants During Winter
Houseplants require specific care during the winter months, as they can be affected by low light and dry air. Here are some essential tips to keep your houseplants healthy.
Light Requirements
As daylight hours shorten, houseplants may not receive sufficient light. Rotate plants periodically to ensure they receive equal sunlight exposure, and consider using grow lights for those that require more intense light.
Watering Needs
Most houseplants go into a period of dormancy during winter, meaning they require less water. Always check the soil moisture before watering, and be careful not to overwater, as this can lead to root rot.
Humidity Levels
Indoor heating can significantly reduce humidity, causing stress to houseplants. To maintain humidity, consider the following:
- Place a humidity tray filled with water and pebbles beneath your pots.
- Mist the plants regularly to keep moisture levels up.
- Group plants together to create a more humid microenvironment.
Fertilizing
Most houseplants do not require fertilization during the winter months as they are not actively growing. Hold off on feeding them until spring when growth resumes.
Common Mistakes to Avoid
While overwintering plants is generally straightforward, there are common mistakes that can jeopardize their survival. Here are some pitfalls to watch out for:
Overwatering
One of the most common mistakes is overwatering plants during winter. Always check soil moisture before watering, as plants in lower light conditions often need less water.
Neglecting Pests
Before bringing plants indoors, it’s vital to inspect them for pests. Failing to do so can lead to infestations that spread to your other houseplants.
Incorrect Temperature Conditions
Ensure that plants brought indoors are placed in appropriate conditions. Extreme temperature fluctuations can stress plants, so try to maintain a consistent environment.
Ignoring Light Needs
Many gardeners underestimate the light requirements of houseplants during winter. Be prepared to adjust their location or supplement with grow lights to ensure adequate light levels.
Conclusion
Overwintering your plants is an essential part of maintaining a successful garden and ensuring that your plants thrive from one season to the next. By understanding which plants require protection and employing the appropriate methods, you can help your garden survive even the harshest winter.
Whether you choose to bring plants indoors, use cold frames, apply mulch, or store bulbs, the right approach will allow your plants to rest and rejuvenate during the colder months. By taking the time to care for your plants in winter, you not only protect your investment but also set the stage for a flourishing garden in the spring.
With careful planning and preparation, you can successfully overwinter your plants and enjoy the beauty of gardening all year round. Happy gardening!