If you purchased tubers in a bag they probably are in wood shavings or something to help hold moisture. If the tubers look plump and firm, just put them in a brown paper bag and put them somewhere cool, but over 40 degrees, and they will hold easily until you are ready. I have occasionally purchased tubers from big box stores that were pretty dried out, if that is the case, moisten the shavings a little (like a damp sponge) and they will start to re-hydrate.

Alternatively you could go ahead and plant them in pots and get them going so that when you plant them they are already going. Last year I planted up most of my tubers in pots about a month before I could put them in the ground, I got flowers appreciably earlier.

Mandolls, thanks for your reply.

If I grow them in pots now, how much light do they need indoor?

Will SE bay windows be enough for dahlias? I guess I can move them to the NW windows in the afternoon if needed since there is only 1 or 1.5 months left before last frost.

If you are going to store these small tubers clumps until they can be planted, put them into a PLASTIC bag to preserve what moisture they have. You could add a bit of water but they should be OK in the plastic bag even at room temperature. Dahlias do not re-hydrate real well so best not to dry them out in the first place.

Its true they dont like to be dried out. I was assuming that they came in plastic bags (any I have seen at the big box stores were packaged that way). I have however had some luck with rehydrating dried out tubers. Soaking them in water for a few hours before planting them up helped, and most of them sprouted.

Dave - Once the tubers come up through the soil, (which will take a while if you plant them 6 inches deep), the more sun they get the better, However, last year mine did not get a lot of sun in the only window I had available, and they all did fine. Once it warms up, if you can move them outside (light shade at first) during the day, it will help.