Well, Can't say that I have heard of anything that will stop a dahlia from growing to its height potential. Perhaps if you wanted cactus dahlias that were 24 inches tall.......then maybe researching and finding dahlias that only grow that tall would be the answer. Research before buying and planting can prevent a lot of woes. Its also best to put the stakes in the ground when you plant the tubers so you don't damage the tuber later. Most taller varieties will have to be staked or will end up laying on the ground.

Happy Gardening,
Sierra