Question
I live in southwestern New Hampshire, zone 5, I believe.  My daughter bought me a package of 15 varied dahlia bulbs and I did not get them planted in time.  I didn't know where she wanted them planted and I didn't know when they should be planted.  I noticed than they have started to grow within the package and I want to know if I can overwinter them in my cellar and plant them next spring.  Thank you.

Answer
Hello Jean

As long as your cellar is cool and frost free, you can certainly over-winter the dahlia tubers there.  

Take them out of the packaging they came in and if the growth you have noticed is long and spindly, cut it off and place the tuber upside down in a tray for a few days to allow it to dry out.  

Finally pack the tubers in trays of dry peat or sand (the right way up!).  Check them occasionally during the winter.  If any of them seem very dry and wrinkled, place in a bucket of tepid water for a couple of hours, until they plump up again, then pack back in the peat/sand.

If you find any areas of rot, cut them out with a clean, sharp garden knife and dust with a fungicide (easily available from a garden center or a hardware store) and once again, pack them back in the sand/peat

As these are new tubers delay planting them until late May or early June.  In successive years (assuming you lift them in the fall*), plant them out a little earlier - late April/early May.

Always plant in a sunny spot, and stake taller growing varieties.

I hope you have a lovely display next year!

Gill


*  Dig up the dahlias when the first frost has blackened the leafs and stems.  Cut off the stems about 2"-3" from the tuber and place them upside down in trays for a few days to dry off.  Once they are dry, brush off as much earth as you can and inspect for signs of rot and treat as I've described above.

Follow the advise given for winter storage.