have you heard of any commercial fertilizer that cannot be used for plants that are intended to be eaten?

As long as it is strictly only a fertilizer, no. The problem is many lawn and orchard fertilizers come with added pest, fungus, and other disease control chems that may not be approved for use on food crops or only approved for application prior to fruit set.

You indicate you don't know the ingredients in this so if you can't contact the company to find out what they are I'd recommend not using it.

Using a known, approved-for-use on food crops synthetic is fine. Using an unknown is something else.

Dave

I would never use a product without a list of ingredients on the label. It shouldn't be sold that way. If it's just the MSU orchid formula that's been illegally repackaged, those ingredients are just fine.

Thanks for the advice. It's from a local orchid show years ago and says only "MSU formula" plus the dosage. I guess you are right that it's a repackage.

Sources online shows the MSU formula (for RO water) should contain (13-3-15):
Nitrate Nitrogen 12.5%
Ammoniacal Nitrogen 0.5%
Phosphorus as P2O5 3.0%
Potassium as K2O 15.0%
Calcium 8.0%
Magnesium 2.0%
Iron 0.17%
Manganese 0.08%
Zinc 0.04%
Copper 0.04%
Boron 0.01%
Molybdenum 0.01%

From my limited knowledge, those ingredients look fine to me. I just want to make sure it doesn't contain some heavy metal or strange hormone. Although I have no idea whether their concentration matters or not.

On researching this question, I found that actually it's not easy to say whether a product is approved-for-use on food crops, as Dave said. Other than those that are specifically designed for vegetables, many generic fertilizers don't mention whether they can be used on food crops or not. Like the DynaGro Foliage Pro I have been using, I couldn't find a reliable source that states that product is safe for food crops.

DynaGro Foliage Pro says "use to maintain healthy, controlled growth on foliage plants and trees" (which they define as ferns and palms). So it doesn't should like a vegetable garden fertilizer to me. The only garden vegetables I can think of where it might even be applicable would be leafy greens.

The only product they list for vegetables is their so-called General Purpose Liquid Grow but then instead of vegetables they list application rates on it for African Violets and in hydroponics.

If vegetables are what you are growing then there are many much better vegetable garden fertilizers out there.

Dave

Fertilizers are like cleaners/soaps. They take the same cleaner and market for various uses. So goes for the fertilizers. Add or subtract from a given NPK and market it for orchids, tomatoes, roses et cetera. The trace elements shown in the analysis is not going to harm anything in small amounts.

I would use the one in question in 1/2 strength, occasionally on just about anything I want until it is all gone.

Got it. Thanks guys! I'll just use it for now and look for something better for the veggie in the future. I hate wasting. :)