Natural and organic are two different things but can get confused if you are not aware of the difference. Organic is grown with out the use of synthetic/chemical fertilizers, pesticides or herbicides. Simply speaking, for the most part the soil is fed as a living thing and the plants grow from the nutrition the microbes, worms and other living things in the soil change into nitrogen and other nutrients from organic matter. "Natural," just means it grows. The plants can have all the chemical sprays and fertilizers put on them and it still can be called natural.
We chose organic because we did not want the chemicals in the feed. Pretty much as simple as that. some will say that natural is safe, and I won't argue. I just feel better knowing certified organic does not have anything synthetic used in controlling weeds, pests or growth.