Re: breaking them up ... it depends on the size of the pot. I was growing about 50 roses in containers in the San Diego area. Yes, I broke them up for the smaller pots with mini roses, but with the HTs, floribundas and shrub roses, I did not break them up because those roses were planted in much larger containers.
Ants will actually bring aphids to a rose so that they can harvest the honeydew. Before I started using the cinnamon sticks, I had to wash the aphids off daily. Afterwards, that was no longer an issue.
I've used cinnamon sticks on my sliders, inside my window screens, etc and have never had an ant inside the house either. Why they work ? I really don't know. I just know it works.
Smiles,
Lyn