Budbreak: Refers to the start of the new growing season, when tender green buds emerge in early spring’s warm temperatures; typically March in the Northern Hemisphere and September in the Southern Hemisphere. The vines are especially vulnerable to frost at this stage.
Frost: Subfreezing temperatures, which can damage or kill vines, are especially harmful in the early spring after budbreak. Heaters known as smudge pots, wind machines that keep cold air from settling in the vineyard and aspersion (using water sprinklers to form a protective barrier of ice around young vine buds) may be used when frosts are forecast. In the winter, before budbreak, a moderate frost can be a blessing; it hardens the vine’s wood and also kills spores and pests living under the bark.