Most Miracle Grow products are foliage feeders. There is nothing wrong except in some people's minds about using chemical fertilizers. I use the cheapest 10-10-10 fertilizer I can buy. Some use low nitrogen fertilizers but in my soil it is needed. I definitely do not use bone meal because of the risks that it has. Much of it is from what is called downer animals, ones that have died of disease or just died. Many people think it is safe but for certain diseases the heat and chemical treatments that are used in the preparation is not good enough for me to risk it.

Bone meal is just a byproduct of the animal slaughterhouse. It does not come from diseased animals.....,,.it comes from the same ones you eat!! In fact, there are pretty strict regulations about how it is processed so very little to fear from that. I wouldn't use it for this purpose as it is not a complete fertilizer and so lacks some essential nutrients while going heavy on the P.

And Miracle Gro products are not necessarily intended as foliar fertilizers. They are just a water soluble fertilizer like a zillion other brands. Very few plants are able to survive on just foliar applications of nutrients and typically you water in these materials to the soil surrounding the root zone where the plant roots take up the nutrients, as nature intended.

I'm not sure where you read that chemical fertilizers (actually synthetic fertilizers, as all fertilizers are comprised of chemical compounds, regardless of their derivation) are not advised for peonies. The plants can't tell the source of the nutrients they receive - by the time the nutrients are absorbed, they are all in the form of inorganic soluble salts. So you can continue to use your MG ( as a soil drench, not a foliage application) or any other general purpose fertilizer, either organic or synthetic - RoseTone or GardenTone, a prepared 10-10-10 or similar product or even a slow release like Osmocote. They all work.

The primary issue is whether you even need to fertilize these plants. Generally, fertilizing anything not being grown in a container is not a routine practice but a matter of knowing if your soils are deficient in any major plant nutrient. If the plant appears healthy, is growing well and flowers well, then likely you don't need to do anything.

That is fine if you believe it except I have seen the bodies being delivered to a rendering plant. The second step is sending the bones off for processing.

I use BulbTone on my peonies, early spring and after bloom is done. Used to not fertilize at all and they grow just fine. I have seen a marked increase of first year blooms and larger blooms on mature plants since I started using it.