I am sorry to hear of your experience with Miracle-Gro Potting Mix . The soil you purchased is a natural product. We do not sterilize the soil nor do we claim to on the package. In addition, soils and mulches may become infested with insects while in storage as they are waiting for sale.
In some cases, soils become infested with fungus gnats. Fungus gnats enter the bagged product through the tiny air holes in the bag that are necessary for the soil to "breathe". Fungus gnats are often mistaken for fruit flies. They do little damage but are unpleasant if present in large numbers. These insects do not feed upon plants, but lay their eggs in soil that contains organic matter. After a week the eggs hatch, and the larvae crawl through the upper layer of the soil. The larvae are white, 1/4 inch long, and have black heads. They feed on fungi that grow on organic matter. The larvae usually do not damage plants but, when present in large numbers, may feed on the roots of some plants, killing very young seedlings. The larvae feed for about 2 weeks before maturing into adults. There can be many generations in a single year.
Below are some steps you can take to control these fungus gnats:
1. Let the soil dry out more between each watering. Dry soil can help kill the larvae. Most people tend to over water their plants, and this can make the problem worse. It's especially important to drain the saucers of excess water. Anything left after an hour should be poured out.
2. Apply at least 1/2 inch of sand on top of the soil of potted/container plants. Larvae cannot burrow through the sand and will die. Sand should be left on the container for several weeks, until the problem is solved.
3. Insects will not disappear overnight. It may take several weeks but you should begin to see a reduction in insect numbers. All houseplants in the home should be treated.
Miracle-Gro does not recommend sterilizing soil. Soil is a living habitat for plants; microorganisms live in the soil that are beneficial - even essential - to the growth of plants. When soil is sterilized, these beneficial organisms are destroyed. Instead of sterilization, we recommend that soils be composted to destroy harmful disease-causing bacteria and weed seeds, leaving beneficial organisms unharmed.
We want you to be confident in our products. For this reason, we offer a product guarantee to our consumers. At your earliest convenience please contact us to see what can be done. You may visit our contact page by clicking on the following link http://tinyurl.com/7ag7a3n