You can see why the common name for this Aconitum is giant monkshood. In its native environment in mountainous areas of Russia and China it can send up spires of bloom reaching 7 to 8 feet tall.  This is an impressive back of the border plant, and a tough one. It can take periods of drought in stride, and handle Siberian winters.

Aconitums are commonly known as monkshood, because the upper
sepal of each flower resembles the hoods of medieval monks. They
attract a variety of butterflies and moths, and are the primary food
source for Old World bees. Another common name, wolfbane, refers to the
poison made
from this plant's roots, which was used to tip hunting arrows.
Medicinal (and poisonous) uses of this plant date back to ancient times.
What's the difference between a medicine and a poison? Dosage.