I think it depends on which "granular fertilizer" you used. I use Osmocote, which is "timed release", and the version I use (available on Amazon in 50 lb bags) is labeled to last for 9 months (there are various versions). So, I do not worry about mine being used up/dissolved by the rain.

The exception to the above comment is of course if an actual garden bed got seriously flooded and had a water current running in it which could have washed it away. I do have one bed between the sidewalk and the street which has had that happen a few times in our very very wettest winters - the raging river in the street gutter overflows into that bed, and washes away the rose food, along with any mulch or compost I have recently put on that bed. The roses are still clinging on for deaar life, but they are not happy. The only solution is to re-apply the food and the compost when it looks like the rainstorms have let up a bit. This winter, here, that might not happen for a month or two from now.

Jackie

I'll check the bag-I think it's supposed to last a few months...Thank you for your help, Jackie.