Folliar feeding is only good if the plant needs it (if your leafs are damaged from a def or somthing) your better just root feeding if your plants are healthy
fish mix and bat gauno is my fav. thing to use fish mix has better results tho
you can use any organic fert. as a folliar feed
if you do need to foliar feed some time do it during vegging only and when your lights are on
I use sea kelp foliar spray...Growtech makes it I believe. I use it on clones in the first few weeks because they can only uptake nutrients after they root. Seems to work beautifully.
I also use it a few times in veg. and a few times in the first 2 weeks of flower. Then discontinue.
remember to spray UNDER the leaves, the stomata ( pores ) are there.
The stomata intake nutrients as they also take part in gas exchange.
I have 9 plants going right now that I have been folliar feeding in combination with soil feeding using a really weak concentration of miracle grow all purpose plant food. I use a little less then half a tsp in a normal spray bottle(40 fl ounces) for folliar feeding, and a little more then a tsp per gallon of water for soil feeding. I spray the plants leaves every day and feed the roots every three days. I know miracle grow isn't to popular with weed growers but so far it's been working great for me.