Feeding tomatoes should not be that complicated. Use a complete plant food with micronutrients and the 3 major nutrients (NPK) and your tomatoes and other vegetables will get all the nutrients they need. I apply Osmocote around the base of each tomato plant in the spring and then use a liquid plant food like Miracle Grow (they make a formula especially for tomatoes) once the weather warms up in June. Follow the instructions on the fertilizer package no matter what type of plant food you use as too much fertilizer can damage plants. You will learn to know by looking at your plants when they need fertilizer. Pale leaves and slow growth during warm weather often means the plants need fertilizer and potted tomatoes need plant food more often than tomatoes growing in the ground. A lack of calcium in the soil can cause tomatoes to crack so a complete plant food with calcium will prevent this.  Some tomato plants may need feeding every week with a weak solution of plant food and some lucky gardeners with great soil can grow beautiful tomatoes with just one application of slow release plant food.  I see some luscious tomatoes in your future. Keep growing, Marianne Binetti