Do not spray moss killer on your garden plot. Instead sprinkle lime on the soil and turn the moss and lime into the soil. Moss does not harm the plants it is simply an opportunist that grows in any damp, dark spot that has low fertility. Adding more organic matter to your soil such as leaf mold, compost, or steer manure would help to add to the tilth of the soil and prevent the moss in the future. Sounds like cool season crops such as peas, lettuce, cabbage, spinach and kale will be your best bets in this partly shaded site. Keep growing, Marianne Binetti