Warning: Miracle Gro

Many gardeners use Miracle Gro fertilizer products to give their plants or lawn a quick boost, and when used correctly, it can make a plant grow larger and greener. Synthetic fertilizers like Miracle Gro provide plants with the nutrients they need, but they may not be the healthiest thing for your soil, your family or the environment.

Fertilizer Burn

Applying too much fertilizer can result in "burning" the plant or lawn. Fertilizers like Miracle Gro contain varying percentages of nitrogen, potassium, and phosphate. In plant food, these elements are made to be quick-release so you can see the effects of the fertilizer within a few days or weeks, but the chemicals are made of different types of salt. Improper dilution or overuse prevents plants from taking water, causing them to wither and die.

Unhealthy Plants

Miracle Gro can be beneficial for giving ailing plants and lawns a short-term burst of growth and energy. But in the long run, it may not be the kind of growth you want. On lawns, synthetic fertilizers contribute to thatching, which deprives grass of light and water. In vegetables and flowering plants, Miracle Gro can reduce blooms and fruits because the high nitrogen content that makes plants green and lush also causes plants to direct all their energy to leaf growth instead of fruit or flowers.


Plants do not use all of the elements in one application of Miracle Gro. The quick-release ingredients that don't reach the plants are leached out of the soil within a few weeks, and the plants will require further applications to get enough nutrition. The fertilizer that is leached out goes into storm drains, groundwater and waterways, causing pollution and endangering wildlife.

Damage to Soil

Synthetic fertilizers feed plants, but they do not feed the soil and can actually harm useful micro-organisms. Organic fertilizers are slow-release, and they work by feeding the microbes that break down chemical elements so plants can take them up. Miracle Gro provides nutrients in a form plants can take up immediately, but the salts and other chemicals upset the balance of the soil and can kill beneficial microbes, fungi and worms that keep the soil healthy.

Dangers for People and Pets

The warnings on the Miracle Gro label state many of its dangers. If ingested, Miracle Gro can cause vomiting and irritation of the mouth, stomach and esophagus. If inhaled, it can irritate or damage airways and lungs. The label also recommends avoiding contact with skin and eyes and immediate washing if contact does occur. People and pets that touch plants or play on grass that has recently been fertilized with Miracle Gro can become ill or get an unpleasant rash.