I have several spiderworts in the gardens
I have found they behave quite differently
The bright magenta like above photo , has the worst habit . It grows sparsely(not clump forming) and spreads more than I am comfortable with ....so It has been confined to a pot and doing well.
The wild form, taller and purple/blue behaves,and forms nice clumps although it gets ratty looking in late summer if grown in sun, in that case I just cut it to the ground.
I have one called ''billberry ice'' and It neither spreads or multiplies much at all.
''Osprey'' disappears completely(dies back) by mid July after blooming
