By taking a quick look at the sticker, you can tell if your produce is organic.
Conventionally grown produce will usually have a 4-digit PLU code that starts with the number 4 or 5. What does conventionally grown mean? It means that it most likely was grown with chemical assistance. I say most likely because it is super-expensive for a farm to get their food certified organic and many smaller farms may not be able to afford to do so. If you're buying locally just ask whether or not you're purchasing organic produce.
Here is a picture of a conventionally grown Granny Smith apple from a recent trip to the grocery store.
Certified organic produce will have a 5-digit PLU that starts with the number 9. What does it mean to be certified organic? It means that the produce has not been grown with the use of chemical assistance. The farm growing certified organic food has to adhere to strict standards that get verified by private organizations.
Remember just because a food is organic, doesn't mean its local. Heck, look at the sticker from my latest shopping trip. My Granny Smith Apple, number 94139 came all the way from New Zealand! So while I'm making strides towards incorporating more organic foods into my diet as part of my participation in Project 10, I also want to take steps to buy more locally grown produce - or at least produce from the USA!
The Produce Marketing Association, the group of people who decide the PLU numbers, created them as an optional convention for retails to help with their inventory management. That means don't get scared if your produce has some wacky numbers that aren't either of the above.
There is one thing to keep in mind, however. As part of the optional naming convention, the PMA also suggested that genetically modified/genetically engineered produce (or GMO) have a 5-digit code starting with the number 8. What does it mean to be genetically modified? Basically that science has messed with the genes of the original produce. It is no longer 'natural.' I've never seen produce start with the number 8. I'm pretty sure farms using GMO produce aren't going to go out and advertise that fact willingly, so unless your produce is certified organic, there is still a chance it has been genetically modified.
It's pretty impossible to find an accurate list of genetically modified foods, and even harder to find information that isn't heavily slanted politically. I urge you to do some research on GMOs if it is something that concerns you. I hope to provide more education here in the future.
If you want to learn more about Project 10, here are my previous posts: