Question
HI Elyse what you think of foliar fertilizers for a tomato plant?  I was advised by a garden shop person that a seaweed foliar spray (direct spray-on, no water needed) is very effective as an 'instant boost' for growing plants.  

He also advised me to buy a normal granular tomato fertilizer too, as the foliar spray focused on nitrogen and the granular was much higher in potassium content.  Is applying both foliar and water-soluble granular fertilizer ok?

Answer
I've never seen a reason to use foliar fertilizers on tomatoes. It's good for a boost, as the salesperson said, useful if a plant is weak or sickly, but it won't help fruit production, and therefor I don't feel it's worth it. I would stick with the granular fertilizer, or simply add bone meal and perhaps lime if needed.

Elyse