The buds swell before they burst.

After the leaves fall off, in November generally, the buds become visible. They are located in the axils of the leaves (the point where the leaf is attached to the vine).

As the temperature rises in February and March, so does the sap; the plant is roused from its winter slumber and the buds begin to swell, getting ready to burst.

The protective floss appears (cotton).

The case of the bud splits to reveal a tangle of filaments that look like fluff. This is the floss or down that protects the cluster (with no grapes as yet) and the leaves that are already formed.

The leaves and clusters break out.

The floss disappears, revealing the leaves and clusters (with no grapes as yet) which open and develop.

rowth continues in this way until the fertilization phase: flowering.