Spray slow cooker with cooking spray or line with slow cooker bags or liner.
Place potatoes in the bottom of the slow cooker. Top with onions.
Press 3 cloves of garlic on top of potatoes. Sprinkle with salt & pepper.
Add chicken to the top of the potatoes. Add lemons and rosemary. Sprinkle with poultry seasoning.
Place lid on the slow cooker and cook on low for 4 hours.
After 4 hours check the internal temperature. It should be 165 degrees.
If done, remove the rosemary & lemon and serve. Season to suit your taste. I had to add additional seasoning. Enjoy!