What will happen to my plants if they reach sand??

Question:My porch has a 3x20 raised platform to plant plants in. It was filled with sand. I bought about 15 bags of top soil, which ended up making about 4-5 inches of top soil on top of the sand. I planted some tomatoes, flowers, and vines in the top soil. My concern though, is will my plants die when their roots reach the sand? Thank you for your help!

Answers:
No they will not die. Florida is nothing but sand and we grow vegetables and flowers all over the state.

If they start to look less than excellent water them with Miracle Grow.