Identify 2 controls in this experiment:
Identify the independent variable:

A scientist wants to determine if using different types of fertilizer (Miracle Grow, Bloom, and Big Grow) on tomato plants affects how big the tomatoes get. The scientist takes 6 tomato plants. All the plants are the same age and height. All the plants are in the same size pots. The scientist adds Miracle Grow to 2 of the pots, Bloom to 2 of the pots, and Big Grow to the last 2 pots. All the plants are put in the same location near a window. The scientist measures the size of the tomatoes on each plant every week for 3 months.