Can the juice from bay laurel leaves kill weeds without synthetic chemicals? You extract juice from one kilogram of leaves. Then you dilute it to four strengths. A fifth pot gets plain water as a control. Each mixture goes into a spray bottle. You spray the matching pot of weeds every day for 12 days and observe the changes. Higher concentrations kill the weeds faster. At full strength, weeds begin changing color by day 4 and die by day 7. The control weeds stay healthy throughout.