I use Pro Organic plant food spray as a foliar fertilizer (yes… I spray it directly on the leaves!)
The key to this type of fertilizer is timing: avoid sunlight and heat by spraying your leaves in the late evening or early morning (not on a super sunny day!)
This fertilizer can be used on indoor and outdoor plants! My favorite part: There’s no awful smell, like I’ve been dealing with when I use fish fertilizer… yuck.