Raspberry canes are perennial plants with biennial shoots that thrive across a wide range of climates. Whether you should cover them depends on the specific environmental threats they face in your location. Covering is a targeted practice, serving as insurance against predictable damage. The decision to use a protective layer depends on the season, expected weather severity, and the presence of pests. Understanding the timing and purpose of covering ensures the highest potential for a successful harvest.
Determining When Covering is Necessary
The need to cover raspberry canes is tied to protecting the plant’s health from three primary threats.
The primary reason is shielding the canes from extreme cold and desiccation during dormancy. In regions where temperatures regularly drop below 10°F or where snow cover is insufficient, covering prevents winterkill caused by deep freezes or windburn. Floricane varieties, which fruit on second-year growth, are susceptible because the canes must survive the winter intact to bear fruit the following summer.
A second reason for covering is to protect tender new growth from late spring frosts. While dormant canes are cold-tolerant, delicate flowers and emerging buds can be damaged by freezing temperatures after the plants break dormancy. A sudden cold snap can severely impact the season’s yield. This temporary protection is typically applied overnight and removed the following morning once temperatures rise.
The third threat occurs during the fruiting phase, requiring a physical barrier against wildlife. Once berries ripen, they attract birds and small mammals. Pest exclusion ensures the harvest remains for you. This type of covering is installed after pollination is complete and remains in place until the end of the harvest.
Selecting the Appropriate Cover Material
The material selected must correspond to the specific threat you are trying to mitigate.
For protection against birds and small animals during the summer harvest, fine-mesh bird netting is the standard choice. Netting with a mesh size of approximately 20mm allows for sunlight and air circulation while effectively excluding pests. This material should be pliable woven polyethylene that can be easily draped over the canes without causing damage.
For temporary protection against spring frosts, lightweight fabric covers are effective. Horticultural fleece or floating row covers are permeable materials that raise the temperature underneath by several degrees, shielding buds from damage. These fabrics are light enough to lay directly over the canes, though structural support helps prevent tearing or crushing of new shoots. Old bedsheets or blankets also serve as a temporary solution for a single cold night.
For severe winter protection in the coldest zones, a heavier covering is required for insulation and a windbreak. Burlap or specialized netting can be wrapped around bundled canes to minimize exposure to desiccating winds. Alternatively, canes can be bent down to the ground and covered with thick mulch, straw, or soil. This method relies on the ground’s residual heat and the material’s insulating properties to maintain a stable temperature.
Practical Steps for Installation and Removal
The successful application of any cover depends on the technique used and the timing of its removal.
When installing netting for pest control, construct a simple frame or use existing trellises to suspend the material above the canes. This prevents the netting from resting directly on the fruit, which allows birds to peck through the mesh. The edges of the netting must be secured tightly to the ground using landscape staples, clips, or weights to prevent animals from gaining access underneath.
For winter protection, tie the dormant canes into bundles to prevent wind damage. If using burlap, ensure the wrap is secured but not so tight that it restricts air circulation, which prevents mold or rot. When using the “bend and bury” method, the canes are laid down in a shallow trench and covered with soil or mulch. This technique is best performed after the canes have entered full dormancy in late fall.
The removal of protective coverings must be timed carefully to prevent damage to the emerging plant. Winter coverings should be removed in early spring before the buds begin to swell and growth is initiated. Removing the cover too late can result in pale, weakened growth due to lack of light, or damage during the unearthing process. Frost covers are removed immediately after the danger of frost has passed, ensuring the canes receive immediate sunlight and airflow.