Winter Survival of Small Fruits
Helping small fruits, such as blueberries and brambles survive harsh winter conditions it not just an issue in the fall, but relates to cultural practices carried out all through the year. The nutrient status of the plant affects cold hardiness. That is, if the plant is deficient, particularly in phosphorus or zinc, winter injury is likely. On the other hand, if plants have too much nitrogen or potassium in their tissues, they will not harden properly, and again, winter injury can occur. Following proper fertilization practices is clearly important. Late fertilization will delay the hardening process. Brambles and blueberries should not be irrigated after mid-September unless under severe drought stress. Planting a cover crop around these crops helps remove excess water and nutrients from the soil to plants properly harden.
Carbohydrate status is also important. This relates to leaves being able to do their job in producing "food" for the plant. Plants entering the winter with a shortage of stored carbohydrates are more susceptible to injury. Proper pruning allows plants to receive more light, allowing for more carbohydrate production.
The important fall practice is mulching. Mulch helps prevent soil heaving in newly planted blueberries. However, don't apply mulch too early. Wait until low temperatures have been sustained for at least 3 nights. If possible, it's best to mulch justbefore the first heavy snow. Resource: Cornell Small FruitNewsletter.