|My garden is in full sun, the tomato plants are staked upright yet the bottoms of the tomato turn black. Is it the soil, water, or lack of minerals in soil?|
|What you describe sounds suspiciously like Blossom-end Rot, a disease aggravated by widely fluctuating soil moisture, high temperatures, too much nitrogen fertilizer, and a deficiency of calcium in the soil.
Have your soil tested and adjust the soil to a pH of 6.5 to 7.0. Don't over-fertilize, don't plant tomatoes where drainage is poor, mulch the plants with organic matter to help retain moisture, and try to ensure uniform soil moisture by watering deeply once every 7 to 10 days, making sure water penetrates at least 12 inches deep into the soil.
Better luck next year with your tomatoes!