Be patient. You do not say which formulation of Miracle Gro you are using. There are several different formulations for different crops. Look for one specifically for tomatoes or for boosting flowers. The middle number on the formulation will be high such as 5-10-5. If the first number is high it will promote leafy growth rather than the flowers and then fruitsthat you want. Any fertilizer used for lawns will have a high first number. Fertilize and keep the plants well watered and I expect that you will have flowers developing before long.