I haven't found it to be a rampant grower, mine is in morning hot sun and afternoon shade. Perhaps it hasn't spread too far because the field mice had a field day with it this winter. They apparently found it quite yummy and/or great nesting material.
Her in the Blue Mountains,Australia,this plant can become a real pest when planted in the ground as it covers all available shrubs & trees. We have a warm temperate climate & sandy soils & no field mice to keep it under control
I'd be more than happy to send a large shipment of the field mice that inhabit my garden to you for SASE. :-)
They also love Lambs Ears and Rose Campion for nesting materials...I removed the last of the Rose Campion in the spring of 2003. Just about had a heart attack when about a bazillion little baby field mice headed in all directions as I was cleaning up the Rose Campion from under my Lemon tree. There were bushels of shredded leaves under all the plants just loaded with mice. I'm sure it would have made an hysterical video seeing me fleeing from all those itty-bitty mice.