The Supernatural spin-off series, The Winchesters revealed a brilliant method to catch demons that Sam and Dean never used in the original series. The Winchester brothers spent a total of 15 seasons over 15 years hunting every sort of evil monster, and in that time, they implemented a variety of methods to hunt, capture and kill the supernatural beings they faced off against. However, more often than not, the brothers charged in and decided to face the demons head-on, armed with little more than salt-filled bullets and a couple of big knives.
The Winchesters is a prequel series that follows the adventures of John Winchester and Mary Campbell, Sam and Dean's parents, back in their prime hunting days. It looks like the boys parents took a more measured approach to hunting,g as the series has so far seen them hunt primarily in a team along with the incredibly intelligent Lata, and the ever-confident Carlos. Throughout The Winchesters episode 3, "You're Lost Little Girl," they also employed the help of an aspiring witch, Ada Monroe. Ada reveals a method to trap demons inside a plant, which could have been incredibly helpful for Sam and Dean to use throughout their adventures.
How The Winchesters' Demon Plant Trap Works
The scene where Ada traps the demon reveals that this is not an easy feat to perform. In a taunt to Ada, the demon sneers, "You don't have the know-how to pull off a spell like that." It's clear that the method of trapping a demon in this way is either not a simple spell, or the method is only known by a limited number of beings. Ada has a keen interest in the occult, but for whatever reason, the demon does not believe she could have access to knowledge about this kind of trapping spell. The way it works is technically pretty simple, a demon has the ability to possess living things like the Winchesters, but also things that are not human, such as animals and plants. Although, forcing the demon to possess the plant and then remain unable to leave seems to be another issue.
Why Didn't Sam & Dean Use The Demon Plant Trap?
Sam Winchester dabbled in the dark arts and was innately capable of some telekinetic powers, due to being fed demon blood as an infant, but understandably, this power was not always under his full control. Both Sam and Dean applied a number of exorcism spells that all hunters use in order to fight demons and monsters, but more often than not, they relied on special weapons and the support of the angel Castiel to overcome their enemies. Together, they were more than capable of holding back the forces of evil and saving the world time and time again.
In addition, the boys had limited training on how to fight demons. As children, they traveled with their father, John Winchester, but he often kept the boys in their hotel rooms away from immediate danger. It was many years before they came into contact with the secret Men of Letters hideout that John and Mary stumbled into in the first episode of The Winchesters, so they were forced to learn other ways to fight. And while Ada may at a later point in the series share these tricks with John and Mary, so far, only Carlos has seen her perform the spell to trap a demon in a plant. Sam and Dean likely never knew such a spell was possible, and so they never tried to perform it throughout Supernatural's long run.