When the Cadmus lands on the board, is the mine already triggered and ready to go, or does the next action token need to be spent to trigger the mine?
A landed capsule will hatch automatically in the player’s next turn following its landing; immediately by spending 1 Short Skill; or by spending one ARO during another player’s turn. by http://infinitythewiki.com/en/Seed-Embryo You should await until next turn of yours or spend 1 order(actually short skill) or spend ARO in reactive turn of yours to hatch out cadmus. and mine will activate when enemy models 'activate' nearby seed-embryo marker. because it's works like anti-personal mines.(mines only activate when enemy declare order in trigger area.) http://infinitythewiki.com/en/Mines
In other words, you cant spend orders to blow the mine. It is activated from the start, but will only trigger if an enemy makes an action or ARO within its trigger area.