How can I prevent a late spring frost from damaging our fruit crop?
You can take several fairly simple steps to reduce the risk of frost damage to buds, blossoms and fruit without using heaters, commercial wind machines or overhead sprinklers, according to the University of California, Davis’ article Principles of Frost Protection. First, before planting fruit trees of any kind, choose the location carefully. Avoid planting at the bottom of a slope — where frost accumulates — or on cold hilltops. If possible, plant on a north-facing slope to help delay blooming and thus avoid frost damage. The Alabama Cooperative Extension System (ACES) suggests checking seed catalog descriptions and choosing fruit varieties less susceptible to frost damage in order to find varieties that bud and bloom later, when frost is less likely to occur.
For existing fruit trees, ACES recommends putting off pruning until late winter to early spring to stall budding and blooming. If frost is in the forecast when trees are in bloom and the soil has been dry, water the soil a day or two beforehand to a depth of 1 foot (wet soils radiate more heat than dry soils do). To trap extra warmth, the UC Davis article says to cover the wet soil around the bases of the trees with clear plastic until the danger of frost has passed. If you’re using a cover crop, mow it and remove vegetative mulch (at least temporarily). Bare soil — or soil covered with clear plastic — stores and radiates more warmth.
ACES also notes that frost blankets can provide frost protection for fruit trees and small fruits. When you place frost blankets around tree trunks, be sure to anchor them on the ground to trap the soil’s radiant heat.
— Vicki Mattern, Contributing Editor