Want to grow the sweetest tomatoes around? Use baking soda near your plants in the garden.
Just sprinkle a small amount of baking soda on the soil around your tomato plants. (be careful not to get any on the plant itself and be also careful with young seedlings which are more tender.) The baking soda absorbs into the soil and lowers the acidity levels. This will give you tomatoes that are sweet rather than the tart flavor that store bought tomatoes have.