White-tailed deer are common large herbivores in North American gardens and fields, often acting as opportunistic browsers. When natural food sources diminish, deer readily turn their attention to cultivated plants, leading to conflicts with gardeners. Blackberries, belonging to the Rubus genus, are a desirable food source for deer, placing them directly in the path of foraging activity. Understanding the specific appeal of these plants is the first step in managing the relationship between wildlife and your cultivated patch.
Deer Browsing Habits on Blackberry Plants
Deer actively browse blackberry plants, consuming different parts depending on the season and growth stage. The most attractive parts are the tender, first-year canes known as primocanes. These new shoots are less woody and contain higher levels of moisture and digestible nutrients compared to the older, second-year floricanes. This preference for new growth means repeated browsing can significantly stunt the plant, reducing its vigor and fruit production in subsequent years.
Browsing pressure is most intense during late winter and early spring when other native forages are dormant or covered by snow. At this time, the canes and dormant buds provide an accessible food source, even if the plant is protected by thorns. A motivated deer will consume thorny varieties, demonstrating the plant’s desirability when alternatives are scarce.
While the foliage and stems are a consistent food source, the ripe fruit is also highly palatable and consumed readily when available. Deer act as dispersers by consuming the berries and depositing the seeds elsewhere. However, the primary damage to the patch comes from the heavy consumption of the stems and leaves. The loss of this green material compromises the plant’s ability to photosynthesize and store energy for the next fruiting cycle.
Nutritional Value of Blackberries
The high palatability of blackberries is linked to their nutritional profile compared to many other woody browse species. Young blackberry leaves and stems, particularly on the primocanes, are a high-quality food source for deer. This young foliage can contain a crude protein content ranging from 15% to 25%. This is substantially higher than the 6% to 8% typically found in mature, low-quality woody plants.
This high protein level is important when the deer’s metabolic demands are highest. Spring and early summer browsing provides the protein necessary for bucks undergoing rapid antler growth. Does also rely on this protein for milk production and the development of fawns.
The high moisture content of the new growth contributes to its digestibility and appeal, especially during dry periods. Beyond protein, the fruit offers an immediate source of easily metabolized energy and hydration due to its high sugar content. This combination of high-quality foliage and energy-dense fruit makes the blackberry patch a prime foraging location.
Strategies for Protecting Blackberry Patches
Given the nutritional incentive for deer to browse, the most reliable method for protecting a blackberry patch involves physical exclusion. A permanent perimeter fence is the gold standard, but it requires substantial height to be effective. The fence must be at least 8 feet tall to reliably prevent deer from jumping over it.
Alternatively, a double-fence system provides effective protection without requiring the full 8-foot height. This involves installing two parallel fences, each 4 to 5 feet tall, spaced approximately 4 to 5 feet apart. Deer perceive the distance between the two barriers as too great to clear in a single bound, deterring them from attempting the jump.
The mesh material used for fencing should be strong and relatively small, ideally 6 inches by 6 inches or less. This prevents deer from pushing their heads or bodies through the barrier. For temporary protection or small patches, angled or slanted fencing can also be effective, as the slant disorients the deer’s jumping trajectory.
Chemical repellents offer a secondary, less permanent layer of defense, working through either foul taste or strong odor. These products contain active ingredients such as putrefied egg solids or capsaicin and must be applied directly to the foliage. The efficacy of repellents depends on consistent reapplication, which should occur every 2 to 4 weeks during the growing season or immediately following significant rainfall.
A lesser-used strategy is companion planting, which involves surrounding the blackberry patch with aromatic or unpalatable plants that deer tend to avoid. While this approach may discourage casual browsing, it is rarely effective against a hungry or determined deer population.