Can garlic juice stop bacteria from growing? Garlic has long been used as a home remedy. This project tests whether it actually works against E. coli in a lab setting. You prepare three test tubes with equal amounts of milk. Tube A has only milk. Tube B has milk plus E. coli bacteria. Tube C has milk, E. coli, and garlic extract. After two hours, you transfer each sample to a blood agar petri dish and measure colony growth daily for five days. The garlic-treated dish shows no bacterial growth. The dish with E. coli alone grows a large colony each day.