My Dahlia is growing now!

Recently we were putting away some Dahlia bulbs which we bought in Spring but never got around to planting.

We were amazed to find that one had a large green shoot, despite lying in a cold frame without any soil and little water.

Feeling that such effort should be rewarded we potted it up and brought in indoors.

After 3 weeks it is about a foot high.

Will it flower? If it does what will happen come Spring/Summer next year when it should be flowering outside?

thanks for any advice or opinions.