Wine Grape Growing
Glossary
H
HARD PAN. A hard compacted soil layer that develops between tilled and untilled layers when soil is continually cultivated at the same depth or when the soil is too wet.
HEAD. The top of the vine, from which either spurs, canes or cordons may emanate.
HEAT SUMMATION UNITS (HSU). The "heat summation units" for any given growing site is calculated by totaling the number of day degrees above 50 degrees F (10°C) for the entire growing season.
HEDGING. Pruning during the growing season by removing only shoot tops and retaining only the nodes and leaves needed for adequate fruit and wood maturation.
HONEY DEW. Sugary substance secreted by aphids, mealybugs, and soft scales.
HYBRID. A cultivar bred from members of different species.
