Why can stalagmites grow taller than stalactites?

Stalagmites can grow taller than stalactites because they are not constrained by the same structural limitations. While stalactites hang from the ceiling and are limited by their own weight—often breaking if they become too massive—stalagmites rise from the cave floor and are supported by the ground, allowing them to reach heights of tens of meters.1

Additionally, their growth processes differ:
* Stalactites form as water drips from the ceiling, leaving behind a ring of calcite that creates a central canal. They are essentially a thickening of a fragile, straw-like tube.21
* Stalagmites form on the floor from the mineral-rich water that falls from the ceiling. They consist of superimposed layers or caps and lack a central canal, which contributes to their thicker, more stable proportions.21

Because stalagmites are built up from the floor, they do not face the risk of falling due to gravity in the same way that pendant stalactites do, enabling them to achieve much greater vertical growth.1