How do geraniums bloom in the dark?

Now that is the question!?! Every year I dig out the geraniums, shake out the excess dirt and hang them upside down in my basement. For the past 5 years all has seemed normal. In the spring I take them outside and cut the dead branches until I reach live, green growth, put them back in their pots and watch them bloom all summer. What is going on with these geraniums?

You can see the new green shoots, some new leaves and of course blooms! They have not seen more than 1 hour of daylight since October, have had no water and they aren't growing in anything. Crazy I say!
Oh and speaking of crazy yesterday while out walking Max I saw a forsythia bush already in bloom! We had a foot of snow on Monday, yesterday it was 60 degrees - it's no wonder the plant world is in a state of confusion. Typically I put down my corn glutton when the forsythias bloom but that is hard to do when you still have several inches of melting snow covering the lawn.
I did notice this morning that the tulips are now coming up along with the daffodils/jonquils. There are a few crocuses peeping up too. I planted over 40 bulbs last fall but forgot to squirrel proof them with chicken wire so I lost the majority of them but thankfully the naturalize pretty quickly so all is not lost.
It is expected to be another 50+ degree day so hopefully the rest of the snow will melt and I can get back to the butterfly bush and hack it to the ground!