I use a number of different things depending on the strain and I growing and how my soil soil is holding up. I do have certain things that all the plants get though throughout the grow. I use molasses throughout the cycle starting when the plants are about 6 to 8 inches tall, seems to give the foliage a nice little boost throughout the grow. The molasses when used in small amounts 1/2 tsp per 2 liters in the sprayer.
I also give the girls and boys doses of cal/mag when they are switched to flower cycle and they get this every 15 days throughout the flower cycle. Seaweed/Kelp extract is used everyother week on most strains and I do have a couple of my own crosses which seem to like it more every week. This just could be me thinking this on certain strains but even every week you can't hurt your plants. I also, have some amino acid nutes which are certified organic for Costa Rica which are added to the feed whenever the plants show any sign of def. in their grow, I also use this with my waterings.
Fish emulsion is by far my favorite additive for foliar feeding and just to give the plants a special look that nothing else seems to give the plant. One good thing about this I might add is that fish emulsion is a natural antifungal so it helps to ensure no mold from spraying.
Hydrogen Peroxcide is used regularly throughout the grow in almost all foliar feedings and sprayings. I know this will get lots of people saying you will kill your plant!! Well I have used it in all my grows, my gardens and all of my fruittrees on the farm. Works great for mold and fungus. I use it also in my waterings at times, this is dependent upon how my plants look, call it a judgement call.
Baking Soda is used to fight mold when if it is totally out of hand. This stuff can be dangerous to your plants, easy to burn them and upset the plants ph. Have used it for years but also have had many accidents over the years. Today there are many products in the States which will take the place of this but alas, they are not available here.
Foliar Feeding is an art IMHO, takes awhile to understand how it works, when to use it and what to put into it. For the bottle grower, those that think whatever I buy in the store is best to use, have no problems. For those that have knowledge of plants and have a basic understanding of how plants and their enemies work mixing your own ingredients can solve most problems with what they have in their household.
PS.....Almost forgot, sorry medicated this morning...... Manure tea in my sprays........its magic. This goes into my regular spray program