Posted: 08/07/2014 at 12:32
they look very healthy plants. We are in our second year of growing Dahlias. We have ours in 10 inch diameter pots and have these in a large tray that we keep topped up with water. The surface is covered in little clay rocks (just something my husband had lying around) and the plants are in sun for most of the day. We don't do anything special, we just leave the plants to get on with it. I do pick off the dead flowers so we continue to get flowers.
Once they get frosted we cut the foliage off and take them out of the pot to dry off over winter. You can leave them in and just cover with alot of mulch to protect the crown (I haven't done this, just read that you can).
I'm hoping to add to what I have next year.
I'm no expert, I would deadhead when necessary but not sure about feeding them anything special.