Themes

Edelwood is an important object throughout the series and represents the loss of hope. The trees are reminiscent of oak tress in appearance, but have holes that create distorted, terrifying faces of sadness and pain. The Beast makes Edelwood trees from the lost souls of children who have wandered far from home (either literally or metaphorically). The Beast needs the oil to keep the Dark Lantern lit or he will presumably die, but in order to be turned into an Edelwood tree, the person must first lose hope. As seen in the episode "Babes in the Woods," Edelwood branches begin to grow around Wirt as he loses hope of the brothers ever finding their way home. Later, in the final episode, fittingly named "Into the Unknown," Greg also begins the process of turning into an Edelwood tree after doing meaningless tasks for The Beast, becoming weak and tired.

Interestingly, in the brief glimpse the audience gets to see of The Beast lit by the latern, he appears to be made of Edelwood Trees. This begs the question of whether The Beast is a lost soul himself, or simply looks that way due to all the lost souls he has claimed.

A big theme in the series is that nothing is turly as it seems. From the very first episode, Wirt and Greg learn that the large, dog-beast attacking them isn't really a monster at all, and instead just wants Greg's candy. Once it spits up the black turtle it had apparently eaten, it reverts back to a friendly, normal-sized dog. One of the most noteable examples is in the episode "The Ringing of the Bell," where the more monstorous, creepy character of Aunty Whispers is actually good, while Lorna; the sickly, young girl; is the one cursed with an evil entity inside of her.

Of course, there is also one of the biggest plot twists in the show that falls under this theme. Beatrice, Wirt and Greg's guide through the unknown, has been leading them to "Adelaide- the Good Witch of the Pasture," with the promise she will help them get home. In reality, Adelaide is an evil witch who only wants to use Wirt and Greg as mindless servents. Beatrice knew this, and had been leading the brothers there in exchange for a pair of scissors that can "snip her wings" and free her and her family of the curse Beatrice had unintentionally placed upon them in consquence of throwing a rock at a bluebird.

The Black Turtles are animals that appear numerous times throughout Over the Garden Wall. They appear to be connected to The Beast and the black oil of his Edelwood Trees. They have relatively frequent appearances (they appear in more episodes than the series' primary antagonist) and can be seen almost everywhere. Despite this, their origin and purpose remain quite mysterious. Patrick McHale described them as "an imperfection in the quilt" both metaphorically and literally: they are an intentionally unexplained mystery but, like some kind of allegory of inner darkness, they are seen where Edelwood grows and warp the mind and body of whoever eats them.

Two of their most notable appearances are in the episodes "The Old Grist Mill" and "The Ringing of the Bell." In "The Old Grist Mill," a dog swallows one of these turtles after Greg places a piece of candy on its shell. The turtle causes the dog to grow very large; have sclera colored yellow, light yellow, and light blue; and act chaotically. In "The Ringing of the Bell," Aunty Whispers has a barrel of them in her home and can be seen eating one herself without any notable consequence. Despite their odd and mysterious effects on some people, they seem quite docile, as during this episode Wirt and Greg hide in the barrel and remain unharmed and uneffected by the turtles that crawl all over them.

At the end of the day, "Over the Garden Wall" is about hope and determination. While the main antagonist, The Beast, represents the loss of hope, Wirt and Greg defeat him and find their way home by continuing to hope and persevere despite their circumstances. In a perfect sort of coming-of-age story, Wirt faces his fears and anxieties again and again. When he does eventually lose hope near the end of the series after Beatrice's betrayl, once he learns Greg is in trouble, he fights a blizzard and The Beast to save his brother. Greg's constant optimism is also a beacon of hope for himself and those around him. While it sometimes gets him in trouble, it also proves to be productive, such as in the episode "Schooltown Follies," where Greg's plan to host a fundraiser for the school helps not only the school, but also brings joy to the other citizens of The Unknown.

The last few minutes of the series also drives home this theme, as everyone (besides for The Beast) recieves a happy ending. Wirt and Greg get home and are largely unharmed, Beatrice and her family are returned to their human forms and are reuinited, and the Woodsman is also reunited with his daughter again after believing her dead for so long. Even the various characters the brothers met along the way get a brief look into their lives at the end of the series, each seeming content and at peace as winter comes to The Unknown.