Cause of guttation is

Cause of guttation is root pressure. Root pressure is a process by which water is pushed up from the roots into the plant's xylem vessels. When root pressure is high and the soil is well-hydrated, excess water can be forced up into the plant's shoot system, leading to guttation.

Guttation typically occurs during the night or in the early morning when transpiration (the loss of water vapor through stomata) is low, and the plant continues to take up water from the soil.