Soil is the original medium for plants. It can tolerate mistakes such as over feeding and under watering, and is inexpensive and easy to use. Bagged commercial soil is generally sterile, but it could have drainage problems and high amounts of soluble salts. Batches of soil may vary from lot to lot, even from the same manufacturer, and experimenting with different mixes will help the gardener to determine the best choice for their situation. Avoid potting mixes with garden loam, because they must be pasteurized in the oven.