Cutting dahlias for indoor vases is a banner day at my house.  Sometimes just one giant bloom in a shallow bowl of water is enough to brighten the kitchen.  The spectrum of colors is dazzling and I find the effort to plant the tubers in the Spring and dig up at the end of Summer completely worth it!     

There are detailed growing tips for Dahlias from Two Pony Gardens on their website here   - along with information about really fun pizza nights at their place.  They sell dahlia plants and cut-flowers.      

I came home to pots of wilted dahlias after a hot, sunny day.  I was concerned they were goners but after a good drink of water they bounced right back.  Dahlias thrive in consistent moist soil but they are also forgiving - which I suspect has to do with how much water they retain in their stems.