black frost

Black frost is a term used in meteorology to describe frost or cold so intense that it blackens vegetation, typically without the presence of hoarfrost. This phenomenon occurs when the water within plant tissues freezes, causing damage and discoloration.12

Frost, in general, is atmospheric moisture that crystallizes directly onto surfaces when temperatures drop below freezing. Hoarfrost refers to these ice crystals, formed when water vapor turns directly into ice. While hoarfrost covers surfaces like grass and branches, black frost specifically denotes the damaging effect on plants.32

In horticulture, frost is a significant risk, especially for early-season crops and perennial fruit crops in the spring, as freezing temperatures can damage sensitive flower parts. Methods to combat frost include reducing heat loss or adding heat to the environment, such as using heaters or sprinkler irrigation.4