If you want to save a bunch of money time and energy...buy garden tone to add to soil. It is by espoma and works amazing. If you have an agway they sell it in 40 lb bags. About 1 lb per plant seems like a great amount to start with...but more hasn't hurt so far.
http://gardenclub.homedepot.com/build-a-flower-tower/
Basically this is home depot explaining how to make a real easy alternative to a smart pot...but it gave me the idea of utilizing the sides like in their example for greener flowers... Was thinking it would be a neat way to create more tops...
Save your pots...and transplant into native soil amended with supersoil you have left. You will probably want to check them...but more for broken branches or mold...then for water. Watering won't hurt if you can...but a broken branch can lead to rot inside the main stem and kill the whole plant.
This is an amazing answer... espoma is what people who actually want results without spending 10x 's too much use. You need to have a medium...plus ALL necessary nutes...not just the three. Garden tone...does this mixed with promix. You can even cheapen up the mix by doing 50-75% promix...