I have giant mum plants that are growing out of control
by
4ga10821357
+2
they are 4 1/2 ft tall
Suggested Project Book
http://homeguides.sfgate.com/keep-mums-getting-big-71596.html
After they've stopped blooming, split them and re-plant.
And if you don't want them that tall pinch them back in the summer before July 1 as that's the date they start to form buds.
Wish mine did that, how lucky are you! Just trim them back gently.
Trimming should do the trick!