Flower Shell
Flower Shells are standard 12 gauge (0.729 in, 18.5 mm) shotgun ammunition loaded with one of twelve different seed types that can be blasted into the ground.
The ammo is created by a Scandinavian creative lab run by Per Cromwell, who told the Huffington Post that his invention is 100% real and inventory is backordered until February.
There are no indications that method works - the videos (below) only show the seeds being shot into the ground - but it seems plausible.
The bigger problem is that you would be firing a shotgun in your garden.
As you can see, the shell contains gunpowder and primer, making it live ammo.
The company states: "Warning: Seeds fired from The Flower Shell may cause sever damage. The shells must be regarded as real live ammunition."
As a Gizmodo commenter notes:
"Full disclosure: I am a gun owner and an NRA member. That said, this is a breathtakingly bad idea; I'm hoping it really is a joke ... Discharging a firearm in a populated area is illegal in most places and will probably get you arrested. Some nervous neighbor will see you waving a shotgun around, call the cops and there you'll be, confronting a SWAT team amid your chrysanthemums."
Nevertheless, the gardening shotgun is a thing.
Check it out their promotional videos:
Here's one where the "gardener" is spraying the seed with the shotgun: