Blueberry bushes undergo a noticeable change in appearance as the seasons transition from fall to winter. The answer to whether they lose their leaves is generally yes, but this deciduous behavior is not absolute across all types. Shedding leaves is a natural part of the plant’s strategy to survive the cold, allowing it to enter a necessary period of rest. Understanding this seasonal cycle is important for home gardeners to ensure a healthy and productive harvest the following year.
Blueberry Varieties and Leaf Retention
Most blueberry varieties are deciduous shrubs, meaning they drop all their foliage in the autumn after a brilliant display of red and orange fall color. The widely cultivated Northern Highbush varieties, for example, are fully deciduous. They are adapted to regions with colder winters and high chilling requirements. Lowbush blueberries also follow this pattern, becoming completely bare once temperatures drop consistently below freezing.
The exception to this full leaf drop are the Southern Highbush and Rabbiteye varieties, often grown in milder climates. These types are considered semi-evergreen and may retain some or all of their leaves through the winter if temperatures remain above freezing. In very mild environments, these bushes can maintain their foliage year-round. This retention is possible because the warmer winter climate does not force the plant into the deeper dormancy required by its northern counterparts.
The Biological Need for Dormancy
The change in foliage is a visible sign that the blueberry bush is entering dormancy, a phase of metabolic slowdown. This protective state is triggered by the shortening of daylight hours and the onset of cold temperatures, allowing the plant to conserve energy and increase its cold hardiness. Dormancy is a prerequisite for successful fruit production in the spring.
Blueberries require a specific accumulation of cold temperatures, known as “chill hours,” to properly set their fruit buds for the following season. A chill hour is defined as one hour spent at temperatures between 32°F and 45°F (0°C and 7°C). Without this necessary cold period, the flower buds will not develop or open correctly, leading to a poor or absent fruit yield.
For instance, Northern Highbush varieties often require a long chilling period, ranging from 800 to 1000 hours or more. Southern Highbush varieties, developed for warmer regions, have a much lower requirement, sometimes needing only 150 to 300 chill hours. The shedding of leaves is a final step in the plant’s preparation, ensuring its reproductive cycle is synchronized with the return of spring weather.
Preparing Bushes for the Cold Season
Once the leaves have fallen and the blueberry bush is fully dormant, gardeners should perform maintenance to protect the plant through the winter. This is the optimal time for structural pruning, which involves removing any weak, diseased, or dead branches. Gardeners should also remove a few of the oldest, thickest canes annually, cutting them back to the ground to encourage the growth of new, productive wood.
Applying a substantial layer of organic mulch around the base of the bush is beneficial for winter protection. A 2- to 4-inch layer of wood chips, pine needles, or shredded bark helps to insulate the shallow root system from extreme temperature fluctuations and freeze-thaw cycles. Keep this mulch material pulled a few inches away from the crown of the plant to prevent moisture buildup and potential rot.
Even in dormancy, the bushes need moisture, so deep watering should continue until the ground is completely frozen if natural rainfall is scarce. Hydrating the roots helps the plant survive the desiccation that can occur during cold, windy periods. Removing any fallen fruit or leaf debris minimizes shelter for overwintering pests and fungal spores. In areas with high populations of deer or rabbits, surrounding the bushes with wire fencing prevents browsing on the new cane growth.