Place the cubed potatoes in the bottom of the slow cooker in an even layer.
Lay the chicken thighs on top of the potatoes.
In a small bowl, mix the minced garlic, lemon zest, lemon juice, chicken broth, oregano, salt, pepper, and olive oil.
Pour the mixture evenly over the chicken and potatoes.
Cover and cook on low for 6 hours or until the chicken reaches an internal temperature of 165°F and the potatoes are tender.
Stir in the chopped kale during the last 30 minutes of cooking so it softens but keeps some texture.
Taste and adjust salt or lemon if needed before serving.