Winter presents a significant survival challenge for many garden plants due to extreme temperature fluctuations and environmental stressors. Freezing temperatures cause water inside plant cells to crystalize, rupturing cell walls and leading to tissue death. Winter conditions also include harsh, drying winds and intense sun exposure, which result in dehydration known as desiccation or windburn. Preparing plants for dormancy requires proactive intervention to mitigate these threats and ensure they emerge healthy in spring.
Essential Fall Preparations
Preparing plants in the fall focuses on maximizing their natural hardiness before the ground freezes. A few weeks before the first expected hard frost, cease applying nitrogen-rich fertilizers. Fertilizing encourages new, tender growth that lacks the cellular maturity to withstand freezing temperatures, making the plant more susceptible to winter damage.
Proper watering increases a plant’s winter resilience. Deciduous trees, shrubs, and evergreens benefit from a deep soaking just before the soil begins to freeze. This moisture helps insulate the roots and provides hydration to combat the drying effects of winter wind and sun.
Limit pruning activities during the late fall months. Only remove dead, diseased, or broken branches to clean up the plant structure. Postpone major structural pruning until late winter or early spring, as fresh cuts stimulate new, vulnerable growth and provide an entry point for disease.
Ground-Level Insulation and Root Protection
The root system is the most vulnerable part of a plant during winter, especially when the soil undergoes repeated freezing and thawing cycles. This fluctuation causes “soil heaving,” where expanding ice pushes the plant’s crown and shallow roots out of the ground, exposing them to cold and desiccation. Protecting the roots requires applying a thick layer of ground insulation.
Mulch stabilizes the soil temperature, keeping it consistently cold once frozen. This consistency prevents the damaging heaving cycles that occur when temperatures repeatedly cross the freezing point. The insulation also helps maintain soil moisture, preventing roots from drying out during periods of low precipitation.
Suitable mulching materials include shredded leaves, clean straw, and wood chips, which provide excellent air pockets for insulation. Apply these materials four to six inches deep after the ground has frozen hard, typically following the first few hard frosts. Applying mulch too early can trap residual summer heat, potentially delaying dormancy.
Keep the mulch several inches away from the plant’s crown or main stem. This prevents moisture buildup, which can lead to fungal diseases like crown rot or attract rodents that girdle the bark. This exposed ring, often called a “donut” shape, ensures necessary air circulation at the base of the plant.
Above-Ground Barriers and Covers
Protecting the above-ground structure mitigates damage from wind, sun, and extreme cold. Evergreens are susceptible to winter desiccation, or “winter burn,” because their needles continue to transpire (lose water) even when frozen ground prevents roots from taking up replacement moisture. This water loss causes the foliage to turn brown and dry out.
To combat winter burn, wrap broadleaf and newly planted evergreens loosely in burlap or specialized permeable fabric. This material acts as a physical barrier against drying winds and reduces winter sunlight intensity, minimizing moisture loss. For tall or fragile shrubs, creating a cage structure out of stakes and covering it prevents snow load damage and provides a stable windbreak.
Windbreaks are constructed using wooden stakes or snow fencing placed on the windward side of vulnerable plants. These barriers slow air movement, reducing the rate of moisture evaporation and preventing mechanical damage from strong gusts. Place the barrier close enough to be effective but far enough away to allow air circulation.
For low-growing garden beds, such as those containing strawberries or vulnerable perennials, row covers or horticultural fleece provide thermal protection. These lightweight materials trap warmth rising from the soil and protect plants from heavy frost. Depending on the material thickness, these covers can raise the temperature surrounding the foliage by several degrees, buffering against light freezes.
Simple structures like cloches or cold frames are effective for individual, tender plants or herbs. A cloche, often a bell-shaped cover, creates a mini-greenhouse effect, trapping solar heat. Cold frames are bottomless boxes with clear lids that provide a permanent, insulated shelter, protecting dormant plants from the harshest weather while allowing necessary light transmission.
Relocating and Managing Container Plants
Plants grown in containers require a different strategy because their root systems are entirely exposed to the ambient air temperature. The limited soil mass in a pot offers almost no insulation, meaning the roots will freeze solid much faster and more severely than those of their neighbors planted directly in the garden bed. The solution for most tender perennials, herbs, and tropicals is relocation.
Identifying which plants need to be moved indoors is a simple matter of knowing their hardiness zone. Any plant whose required zone is significantly warmer than the local climate should be brought into a protected space. Before moving them, inspect all foliage and soil thoroughly for pests like aphids or spider mites, which can easily infest indoor environments.
Suitable temporary storage locations include unheated garages, cool basements, or enclosed porches where temperatures remain consistently above freezing but cool enough to encourage dormancy. A temperature range between 35°F and 45°F is often ideal for keeping plants dormant without killing them.
Once relocated, the care regimen changes dramatically to accommodate the dormancy period. Plants require minimal watering, just enough to keep the potting medium from completely drying out. Overwatering dormant plants is a common mistake that leads to root rot. Monitoring for the occasional appearance of houseplant pests is necessary, as the static indoor environment can sometimes encourage their proliferation.