Usage patterns
茎が伸びるfor a stem to grow/lengthen
In spring, this plant's stem grows rapidly.
茎を切るto cut the stem
I cut the stem at an angle to make the flowers last longer.
茎が太いto have a thick stem
This tomato seedling has a thick stem and looks sturdy.
茎を折るto snap/break the stem
The strong wind snapped the flower's stem.