Antifreeze can kill plants if enough antifreeze comes into contact with plant roots. The main ingredient in antifreeze is ethylene glycol or C2H6O2, which can kill animals and people if they accidentally drink it. Plants do contain a very small amount of ethylene glycol. This is a waste gas produced from plants metabolizing ethylene, a hormone that helps the plants grow.
Antifreeze first stunts the growth of plants, slows down or halts their reproductive cycle and finally kills them. Plants come into contact through antifreeze in various ways. Motorists may dump antifreeze on the ground or fail to clean up spills. Any antifreeze on driveways or streets eventually washes down the gutters and enters the water table. Antifreeze in the soil, in the water table, or from a public water tap is then absorbed by plants. The ethylene glycol in the plants causes the plant to have difficulties in absorbing water.
Different plant species need to absorb different amounts of ethylene glycol before they stop growing and die. One study published in the May 18, 2011 issue of "International Journal of Phytoremediation" showed that poplar trees suffered a 28 percent decline in growth when groundwater contained 10 grams in each liter of water. In the same study, small potted plants Arabidopsis thaliana suffered a 50 percent growth decline when watered with 40 grams per liter. The plants also failed to germinate.
In order to prevent antifreeze from getting into soil or the general water supply, clean up all spills immediately. Place rags on spill to soak up the liquid. Place rags in a closed container. Keep a drip pan underneath vehicles. Repair any antifreeze leaks discovered underneath vehicles. Never pour unused antifreeze down a sink, on the ground, in a septic tank or into a street gutter. This ensures that the antifreeze will wind up in public water. Take unused antifreeze or perform antifreeze changes at a service station that accepts old antifreeze.
Since 2008, there has been a liquid spray product marketed as "plant antifreeze" that helps plants survive through winter or sudden frosts by lowering the freezing point of moisture inside of the plant's tissues. But this is not antifreeze that can be used in a car. But just because the product for plants is marketed as "plant antifreeze" may confuse consumers who mistake car antifreeze for plant antifreeze. The effects of plant antifreeze wear off after four to six weeks. Unlike car antifreeze, plant antifreeze does not stunt the plant's growth nor kill the plant according to its inventor, Dr. David Francko.