Bleeding

Vines are said to bleed when they lose fluid in spring from pruning cuts. This event can take place over several days, and is generally seen following the first few days of warm spring weather. Individual vines can lose up to 5 l/1.3 gal of water. The liquid which drips from the pruning cuts is mostly water, with low concentrations of minerals, sugars, organic acids, and hormones. This is the first visible sign of the start of the new vine growth cycle, and corresponds to renewed activity of the root system. Osmotic forces create root pressure, which forces water up through the plant. The term is also used occasionally in winemaking; see saignée.