Add 1 tsp. of liquid food coloring to 1 cup of water. Drizzle the colored water onto the soil surrounding the base of a plant. Wait 24 hours for the water to absorb. Apply another identical dose if the color change was not sufficient.
Tomatoes need calcium to achieve their full flavor potential, and calcium is often greatly lacking in our soils. 95% of a dry eggshell is calcium carbonate. When planting your tomato plants crush up (to powder) about 4 or 5 egg shells and put them in the bottom of the hole. Then plant your tomato on top. They'll provide calcium and prevent blossom end rot. --- I'll make sure to use this for the spring