Beginning of the annual vegetation cycle of the vine after winter dormancy (see also under BBCH code). Here, at an average daytime temperature of 8 to 10 °Celsius, those eyes (winter buds) break open that were deliberately left standing during winter pruning. This can be seen some time before, because with the coming of spring and thawed soil, the roots begin to pump plant sap into the above-ground part of the vine, so that droplets of water emerge at the interfaces of cut shoots (the vine "bleeds"). With increasing warmth, the buds swell visibly until the woody bud scales break open and a felt-like spherical hair weave becomes visible, which initially still protects the shoot tip underneath from external influences such as sun and rain.
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