Heat canola oil in a large skillet over medium-high heat. Add onion, garlic and ground turkey. Break up meat into small chunks and cook until browned.
In a slow cooker, place squash, zucchini, parsley and salt. Add the ground meat mixture with pan juices and top with water. Stir, cover, and cook on LOW for 7 hours.
Just before serving, lift lid and stir in spinach, cover and continue to cook for 10 more minutes. Season with additional salt and pepper as needed.