Calibrachoa are not easy to start from seed; I've started a lot of petunias successfully, but last year i tried "Kabloom" and only had a few sprout from quite a few seeds. If I try it again I think I will start them in vermiculite, because I've had good luck with other "difficult" seeds that way.
Melissa, I'm not sure what sort of seed starter trays you are using, but I would suggest planting a couple of seeds together, making sure the medium is quite moist, covering the tray with plastic wrap or a "humidity dome," and crossing your fingers.
Here are the sowing directions from Park Seed:
"Here's how to sow the seeds: they will germinate either with or without light, so begin them indoors in late winter, setting a single seed on top of the bio sponge in your Bio Dome or on top of the grow mix in your seed flats. Keep the temperature between 72 and 75 degrees F, and make sure the bio sponge or grow mix is slightly moist. Germination takes about a week.
Once the seeds have sprouted, add light and keep the temperature above 70 for the first few weeks. They are ready to transplant when they have several sets of true leaves. That's all there is to it!"
I hope you have good luck with them!
