The young mistletoe twigs demonstrate synchronous swinging motions of growth in late May which last until late June. These loosen the annual shoots from their original vertical orientation and direct them toward the centre of the mistletoe bush.
At the same time the organs of new mistletoe branches are produced in the lateral buds which will develop the following spring. After the growth of a pair of leaves the vegetative development stops in mid-June with the growth of a flower head instead of additional leaves.
The berries reflect this change by accumulating nutritive tissue in the mistletoe seed until the end of June, but develop mistletoe embryos from July.
Rhythmic changes in the shape of the developing mistletoe berry indicate that the mistletoe's growth also correlates with the path of the moon across the zodiac constellations.