Home Gardening magic tomato plant food. will feed about 6 tomato plants. 3 cups compost/mulch/dirt 1/2 cup epsom salt 1 tablespoon baking soda 1/2 cup powdered milk 1. mix all the ingredients together in a bucket. 2. place a handful of the mixture into the hole you are digging for your tomato plant. if you have already planted you can sprinkle a handful of the mixture around the stem of the plant and then water.