Hello, I'm Dr. Kara. I have over 20 years of experience as a veterinarian and I'd like to help with your concerns about Jake getting into a little fertilizer.
Luckily none of the ingredients that are in this product are truly toxic to dogs. These are very typical ingredients in a fertilizer.
High levels of nitrogen, phosphoric acid and potash can be irritating to the gastrointestinal tract, causing vomiting and diarrhea, but no long term effects. Given that he ingested very little and he is a bigger fellow I suspect that Jake will have no symptoms whatsoever.
Make sure though to store the container of fertilizer where he cannot get to it however as dogs will be attracted to the odor and will eat it if given a chance. You can also put decorative rocks over the dirt in plants so he cannot get to the fertilizer.
Please let me know if you have any further questions or concerns.