Note: Spinach is highest in calcium, vitamin A, folates, and iron. Kale is right behind spinach in vitamin A content and has three times as much vitamin C. Collards contain a balance of nutrients and provide more energy than all the greens below. Chard is a good source of vitamin E and potassium. Folates are a B vitamin that can help preserve cognitive function and memory. People with Alzheimer's disease may have low folate levels in their blood. Vegans should note that none of the greens contain vitamin B12, which is found only in meat and dairy products. See alsoAntioxidants.    The table below contains some nutrients Planter looks for. 

Source:   USDA Nutrient Database (link in Recipes)