Picture posting is enabled for all :)
You use a tomato feed on plants that you want to flower and poduce fruit. This is a high potash fertiliser.You use a high nitrogen fertiliser on brassicas, etc where you want green leaf, etc .You use a high potash fertiliser (K) for root crops.Then you have the 'balanced' fertilisers which contain the above in roughly equal quantities.valmarg
It was pointed out to me some years ago by a representatives of manufacturers of these products. By people had worked for a few big companies between them, over the years.