I rooted some gardenias last year. I remember asking John for help. Good Lord, if I had known they grow so slow I would have bought full size bushes!! I can see these will not be two feet high for years!!!
Just remember the old saying about perennials: The first year they sleep, the second year the creep and the third year they leap. Gardenias can be bought at discount stores and big box home improvement stores so cheaply you can afford to buy 2 or 3 y/o plants which will grow quickly. But, I always root plants when I prune my gardenias. Your plants will grow more next year spring an summer and leap out the third season. Just hang in there.
Take Terry's word. They will do FINE! Check out the picture I put below - that is a gardenia my mom rooted in 1998, we planted it in 1999. Within a couple of years, it was doing this (all of them do actually). I have to cut them back this coming spring....and it is SOOO much fun to have the history with the plant - you rooted it, etc.
Here is a link that might be useful: One of my gardenias that was rooted