In a small bowl, mix together thyme, oregano, garlic powder, and about 1 teaspoon of salt and 1/2 teaspoon of pepper.
Add potatoes and carrots to the bottom of a slow cooker. Drizzle with olive oil and sprinkle with half of the seasoning mixture as well as half of the minced garlic.
Place chicken on top, drizzle with more oil, and sprinkle with remaining seasoning mixture and minced garlic.
Stir together lemon juice, lemon zest, and white wine and pour over chicken and vegetables.
Cover and cook on high for 2 1/2 hours, or low for 4 1/2 hours.
Add asparagus and cook until tender, about 20 minutes more on high.