Growing Cannas from Seed can be rewarding and lots of fun, too !!!
Take a small triangular file, regular file, pet nail nippers, a small tip dremel, or sandpaper and small pliers (my choice) to hold the seed .. and nick the dark hard outer coat of the canna seed just until you see the white beneath.
Place the scarred seeds in a clear water bottle or container and cover with a couple inches of hot-to-the-hand water and let them sit 24-36 hours. Most will swell in size.
Sow the seeds at this time in a good sterile seed medium and place in a warm out of hot sun area to germinate. Do not let the medium dry out. Cover the pot with plastic wrap, place inside a clear plastic bag, or sow small batches in one of the little recycled soda bottle "greenhouses" we really like for germinating canna seeds. Bottom heat will help, but be careful the seedlings do not get too hot or mold.
When the weather is cold, I place mine in a hooded 10G aquarium with one clear and one blue bulb and a half inch of water in the bottom. The added heat light and humidity bring them up fast. But be careful to keep out of sun and vent the lid and down the lights if temperatures to get too hot.
With good temps, in a week or two, the seedlings will start coming up. After they establish a bit, transplant to 4"-6" pots to well establish before planting out to a sunny location after all danger of frost is gone.
Most cannas started from seed will bloom in the first season. If started early enough, they will rival the performance of spring rhizomes.
Enjoy growing cannas from seed!!! It's a lot of fun :-)