More is involved in starting seeds than popping them into potting mix and letting them go. Some species of plants need to have special requirements met before their seeds can germinate.
Take for example Canna seeds. Yes, I know that Cannas are normally planted as bulbs (tubers) in the early summer. However some varieties of Canna are available in seed form. Thomson and Morgan offer their own hybrid variety as seeds.
Anyway, Canna seeds have an extremely hard seed coat that makes it very difficult for the seed to absorb the moisture needed for sprouting in a timely manner. Canna seeds are also known as “Indian Shot” because they resemble the BB’s used in shotgun shells. As a matter of fact, because they are so hard and dense, at one time they actually were used in shotguns when lead was in short supply.
In order to deal with these difficult seeds, horticulturists have learned that if you “nick” or sand down a small part of the seed coat, water will penetrate the seed and stimulate germination. This “nicking” process is known as “scarification”.
I scarify seeds by rubbing them on sandpaper until a small spot on the seed coat is worn away and you can see the lighter color of the seed underneath. Don’t get carried away though, if you sand too deep, you may damage the living embryo inside.
I haven’t found a really good way to hold the seeds other than with my fingers. Don’t be surprised if some of your fingernail is worn down in the process.
Once your seeds have all been nicked soak them in warm water for about 24 hours. Keep the water warm for the entire soaking period.
These seeds then need to be planted into a potting mix immediately. Once they have been treated by this process, they will not keep.
I suggest you start your Cannas soon. They will need a pretty good head start if you want them to bloom this coming season.
By the way, after this summer is over you can dig the tubers from these plants and save them for planting next year just like any other Canna.